A Strange "c" File with No Extension Keeps Appearing After Deletion but Not After Renaming It


Bree had mentioned they had it too. @Bree - Thank you for welcoming me, but did you open your copy with notepad? Was there any containing text? Just an odd file, and at this point I'm thinking it's just a harmless file maybe placed by MS for some reason or another...
Yes, I opened it. Same as yours, just the single character: \

The appdata folder is on the C: drive. In a command prompt, if you type cd \ it takes you to the root of the C: drive, the name of the file is 'C', perhaps all it is is a pointer to the root of the drive that it's on?

1736310160059.webp
 

My Computers

System One System Two

  • OS
    Windows 11 Home
    Computer type
    Laptop
    Manufacturer/Model
    Acer Aspire 3 A315-23-R9VY
    CPU
    AMD Athlon Silver 3050U
    Memory
    8GB
    Graphics Card(s)
    Radeon Graphics
    Monitor(s) Displays
    laptop screen
    Screen Resolution
    1366x768 native resolution, up to 2560x1440 with Radeon Virtual Super Resolution
    Hard Drives
    1TB Samsung EVO 870 SSD (from April 2026: 250GB EVO 850)
    Internet Speed
    150 Mbps
    Browser
    Edge, Firefox
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    Defender
    Other Info
    fully 'Windows 11 ready' laptop. Windows 10 C: partition migrated from my old unsupported 'main machine' then upgraded to 11. A test migration ran Insider builds for 2 months. When 11 was released on 5th October 2021 it was re-imaged back to 10 and was offered the upgrade in Windows Update on 20th October. Windows Update offered the 22H2 Feature Update on 20th September 2022. It got the 23H2 Feature Update on 4th November 2023 through Windows Update, 24H2 on 3rd October 2024 through Windows Update by setting the Target Release Version for 24H2, and 25H2 on 30th September 2025 through Windows Update by setting the Target Release Version for 25H2.

    UPDATE - 11 April 2026: due to mechanical deterioration this PC has been retired from active duty. The OS with all software and files has been migrated to my System Seven below to carry on as my general purpose 'main machine'.

    My SYSTEM THREE is a Dell Latitude 5410, i7-10610U, 32GB RAM, 512GB NVMe ssd, supported device running Windows 11 Pro.

    My SYSTEM FOUR is a 2-in-1 convertible Lenovo Yoga 11e 20DA, Celeron N2930, 8GB RAM, 256GB ssd. Unsupported device: currently running Win10 Pro, plus Win11 Pro RTM and Insider Dev, Beta, and RP 24H2 as native boot vhdx.

    My SYSTEM FIVE is a Dell Latitude 3190 2-in-1, Pentium Silver N5030, 8GB RAM, 1TB NVMe ssd, supported device running Windows 11 Pro, plus Insider Beta, Dev, and Canary builds (and a few others) as a native boot .vhdx.

    My SYSTEM SIX is a Dell Latitude 5550, Core Ultra 7 165H, 64GB RAM, 1TB NVMe SSD, supported device, Windows 11 Pro 24H2, Hyper-V host machine. Updated to 25H2 on 30th September 2025.

    My SYSTEM SEVEN is a Lenovo Thinkpad T580, Intel Core i7-8650U, 16GB RAM, 512GB NVMe SSD + 2nd 512GB NVMe SSD, a supported device for Windows 11. This is my current general purpose 'main machine'. The installed Windows 11 Home from my System One has been migrated to this machine.
  • Operating System
    Windows 11 Pro
    Computer type
    Laptop
    Manufacturer/Model
    Dell Latitude E4310
    CPU
    Intel® Core™ i5-520M
    Motherboard
    0T6M8G
    Memory
    8GB
    Graphics card(s)
    (integrated graphics) Intel HD Graphics
    Screen Resolution
    1366x768
    Hard Drives
    500GB Crucial MX500 SSD
    Browser
    Firefox, Edge
    Antivirus
    Defender
    Other Info
    unsupported machine: Legacy bios, MBR, TPM 1.2, upgraded from W10 to W11 using W10/W11 hybrid install media workaround. In-place upgrade to 22H2 using ISO and a workaround. Feature Update to 23H2 by manually installing the Enablement Package. In-place upgrade to 24H2 using hybrid 23H2/24H2 install media. Upgraded to 25H2 by Enablement Package. Also running Insider Dev, and Canary builds and Windows 10 as native boot .vhdx.

    My SYSTEM THREE is a Dell Latitude 5410, i7-10610U, 32GB RAM, 512GB NVMe ssd, supported device running Windows 11 Pro.

    My SYSTEM FOUR is a 2-in-1 convertible Lenovo Yoga 11e 20DA, Celeron N2930, 8GB RAM, 256GB ssd. Unsupported device: currently running Win10 Pro, plus Win11 Pro RTM and Insider Dev, Beta, and RP 24H2 as native boot vhdx.

    My SYSTEM FIVE is a Dell Latitude 3190 2-in-1, Pentium Silver N5030, 8GB RAM, 1TB NVMe ssd, supported device running Windows 11 Pro, plus Insider Beta, Dev, and Canary builds (and a few others) as a native boot .vhdx.

    My SYSTEM SIX is a Dell Latitude 5550, Core Ultra 7 165H, 64GB RAM, 1TB NVMe SSD, supported device, Windows 11 Pro 24H2, Hyper-V host machine. Updated to 25H2 on 30th September 2025.

    My SYSTEM SEVEN is a Lenovo Thinkpad T580, Intel Core i7-8650U, 16GB RAM, 512GB NVMe SSD + 2nd 512GB NVMe SSD, a supported device for Windows 11. This is my current general purpose 'main machine'. The installed Windows 11 Home from my System One has been migrated to this machine.
I don't have it.
 

My Computers

System One System Two

  • OS
    Win 11 Home ♦♦♦26200.8457 ♦♦♦♦♦♦♦25H2
    Computer type
    PC/Desktop
    Manufacturer/Model
    Built by Ghot® [May 2020]
    CPU
    AMD Ryzen 7 3700X
    Motherboard
    Asus Pro WS X570-ACE (BIOS 5302)
    Memory
    G.Skill (F4-3200C14D-16GTZKW)
    Graphics Card(s)
    EVGA RTX 2070 (08G-P4-2171-KR)
    Sound Card
    Realtek ALC1220P / ALC S1220A
    Monitor(s) Displays
    Dell U3011 30"
    Screen Resolution
    2560 x 1600
    Hard Drives
    2x Samsung 860 EVO 500GB,
    WD 4TB Black FZBX - SATA III,
    WD 8TB Black FZBX - SATA III,
    DRW-24B1ST CD/DVD Burner
    PSU
    PC Power & Cooling 750W Quad EPS12V
    Case
    Cooler Master ATCS 840 Tower
    Cooling
    CM Hyper 212 EVO (push/pull)
    Keyboard
    Ducky DK9008 Shine II Blue LED
    Mouse
    Logitech Optical M-100
    Internet Speed
    300/300
    Browser
    Firefox (latest)
    Antivirus
    Bitdefender Total Security
    Other Info
    Speakers: Klipsch Pro Media 2.1
  • Operating System
    Windows XP Pro 32bit w/SP3
    Computer type
    PC/Desktop
    Manufacturer/Model
    Built by Ghot® (not in use)
    CPU
    AMD Athlon 64 X2 5000+ (OC'd @ 3.2Ghz)
    Motherboard
    ASUS M2N32-SLI Deluxe Wireless Edition
    Memory
    TWIN2X2048-6400C4DHX (2 x 1GB, DDR2 800)
    Graphics card(s)
    EVGA 256-P2-N758-TR GeForce 8600GT SSC
    Sound Card
    Onboard
    Monitor(s) Displays
    ViewSonic G90FB Black 19" Professional (CRT)
    Screen Resolution
    up to 2048 x 1536
    Hard Drives
    WD 36GB 10,000rpm Raptor SATA
    Seagate 80GB 7200rpm SATA
    Lite-On LTR-52246S CD/RW
    Lite-On LH-18A1P CD/DVD Burner
    PSU
    PC Power & Cooling Silencer 750 Quad EPS12V
    Case
    Generic Beige case, 80mm fans
    Cooling
    ZALMAN 9500A 92mm CPU Cooler
    Keyboard
    Logitech Classic Keybooard 200
    Mouse
    Logitech Optical M-BT96a
    Internet Speed
    300/300
    Browser
    Firefox 3.x ??
    Antivirus
    Symantec (Norton)
    Other Info
    Still assembled, still runs. Haven't turned it on for 15 years?
@Bree (and everyone else) Okay, so here's what I think, now I may be wrong, but I'm pretty sure this is a "marker" file from MS of who's going to get the next features installed whether it be immediately or "down the road" as they describe that some features will be turned off or on for some users who receive this update. I restored a backup of the file that I created a few days ago (trust me, I had this file incredibly protected and locked from attempting to activate should it try). So, as it appears, after the new Cumulative Update for 23H2 (at least for my setup) I haven't received any new features as was described in the OS Build 22635.4660 - since I deleted the "c" file. So, I restored the file and it NOW appears I have all of the new features that are included in this updated build. I believe this file is intended for those who gets the new features as described in the release notes - so leave this file be; as I now have the text located under the icons cut/copy/paste/delete. I think I figured it out, so I'm going to mark this post as RESOLVED.
 

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My Computer

System One

  • OS
    Windows 11 Professional 25H2; Linux Mint
    Computer type
    PC/Desktop
    Manufacturer/Model
    Acer
    CPU
    12th Gen Intel(R) Core(TM) i3-1215U 1.20 GHz
    Motherboard
    Acer Aspire C24-1700
    Memory
    16 GB
    Graphics Card(s)
    Video Card: Intel Arc UHD Graphics (Alder Lake-P 282 GT2) - Integrated Graphics Controller [ACER]
    Sound Card
    Intel Alder Lake-P PCH - cAVS (Audio, Voice, Speech)
    Monitor(s) Displays
    Acer [Unknown Model: ACR40B0]
    Screen Resolution
    1920x1080
    Hard Drives
    SSD: WDC PC SN530 SDBPNPZ-512G-1114
    SSD: TEAM TM8PS7512G
    HDD: WDC WD20JDRW-11C7VS0
    HDD: Seagate ST2000LM007-1R8174 HDD: Seagate ST1000LM035-1RK172
    Case
    Acer AIO
    Keyboard
    Razer Ornata V3 X
    Mouse
    Razer Basilisk V3
    Browser
    Brave, Chrome, Firefox, Edge
    Antivirus
    Microsoft Defender
So, for all those looking into this thread, I think I'm going to mark this post as RESOLVED. because as I previously mentioned in this thread - I came to the conclusion and am almost certain that this mysterious "c" file is a "marker" from MS, for who will receive the new features in latter builds/ cumulative updates. There is sufficient evidence (at least on my part) to prove that new features are dependent on this file that appears to be "hidden" from average users - as this file location is normally defaulted to being hidden and potentially blocked from your "average" user. Yes, it could've been pure coincidence that upon my research and discovery that MS just "decided" to allow the feature, but I'm speculating that this is a direct result restoring this file back to it's proper location. Upon restoration of the file, and a sudden crash (GSOD) these new features became apparent after a reboot. So, please leave this file be and lie where it is should it be on your system.
 

My Computer

System One

  • OS
    Windows 11 Professional 25H2; Linux Mint
    Computer type
    PC/Desktop
    Manufacturer/Model
    Acer
    CPU
    12th Gen Intel(R) Core(TM) i3-1215U 1.20 GHz
    Motherboard
    Acer Aspire C24-1700
    Memory
    16 GB
    Graphics Card(s)
    Video Card: Intel Arc UHD Graphics (Alder Lake-P 282 GT2) - Integrated Graphics Controller [ACER]
    Sound Card
    Intel Alder Lake-P PCH - cAVS (Audio, Voice, Speech)
    Monitor(s) Displays
    Acer [Unknown Model: ACR40B0]
    Screen Resolution
    1920x1080
    Hard Drives
    SSD: WDC PC SN530 SDBPNPZ-512G-1114
    SSD: TEAM TM8PS7512G
    HDD: WDC WD20JDRW-11C7VS0
    HDD: Seagate ST2000LM007-1R8174 HDD: Seagate ST1000LM035-1RK172
    Case
    Acer AIO
    Keyboard
    Razer Ornata V3 X
    Mouse
    Razer Basilisk V3
    Browser
    Brave, Chrome, Firefox, Edge
    Antivirus
    Microsoft Defender
I wonder what it's for? Even Copilot is puzzled.....
And, yes I would like to thank you @Bree as you were questioning Copilot that appeared to be just about correct even though it was puzzled by the file. Thanks again for your help and time!
 

My Computer

System One

  • OS
    Windows 11 Professional 25H2; Linux Mint
    Computer type
    PC/Desktop
    Manufacturer/Model
    Acer
    CPU
    12th Gen Intel(R) Core(TM) i3-1215U 1.20 GHz
    Motherboard
    Acer Aspire C24-1700
    Memory
    16 GB
    Graphics Card(s)
    Video Card: Intel Arc UHD Graphics (Alder Lake-P 282 GT2) - Integrated Graphics Controller [ACER]
    Sound Card
    Intel Alder Lake-P PCH - cAVS (Audio, Voice, Speech)
    Monitor(s) Displays
    Acer [Unknown Model: ACR40B0]
    Screen Resolution
    1920x1080
    Hard Drives
    SSD: WDC PC SN530 SDBPNPZ-512G-1114
    SSD: TEAM TM8PS7512G
    HDD: WDC WD20JDRW-11C7VS0
    HDD: Seagate ST2000LM007-1R8174 HDD: Seagate ST1000LM035-1RK172
    Case
    Acer AIO
    Keyboard
    Razer Ornata V3 X
    Mouse
    Razer Basilisk V3
    Browser
    Brave, Chrome, Firefox, Edge
    Antivirus
    Microsoft Defender
So, please leave this file be and lie where it is should it be on your system.

It was a hidden system file, leaving it alone would of been my first conclusion.
A file named C with no file extension and the content consisting of “\” would appear to me to be a root path. Perhaps obviuously related to a system process or dregs from the swap file perhaps.

But yeah, one would think there would be more info on it.
 
Last edited:

My Computers

System One System Two

  • OS
    Windows 11 Pro 25H2 Build 26200.8524
    Computer type
    PC/Desktop
    Manufacturer/Model
    Sin-built 2013
    CPU
    Intel(R) Core(TM) i7-4770K CPU @ 3.50GHz
    Motherboard
    ASUS ROG Maximus VI Formula
    Memory
    32.0 GB of I forget and the box is in storage.
    Graphics Card(s)
    Gigabyte nVidia GeForce GTX 1660 Super OC 6GB
    Sound Card
    Onboard thingy
    Monitor(s) Displays
    5 x LG 25MS500-B - 1 x 24MK430H-B - 1 x Wacom Pro 22" Touch Screen Tablet
    Screen Resolution
    All over the place
    Hard Drives
    Too many to list.
    OS on Samsung 1TB 870 QVO SATA
    PSU
    Silverstone 1500
    Case
    NZXT Phantom 820 Full-Tower Case
    Cooling
    Noctua NH-D15 Elite Class Dual Tower CPU Cooler / 6 x EziDIY 120mm / 2 x Corsair 140mm somethings / 1 x 140mm Thermaltake something / 2 x 200mm Corsair.
    Keyboard
    Corsair K95 / Logitech diNovo Edge Wireless
    Mouse
    Logitech: G402 / G502 / Mx Masters / Mx Air Cordless
    Internet Speed
    2000/500Mbps
    Browser
    All sorts
    Antivirus
    Kaspersky Premium
    Other Info
    ㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
    TP-Link BE9300 WiFi 7 Bluetooth 5.4 (Archer TBE550E)
    TP-Link TX201 V1 2.5GB Lan

    Grandstream HT812 - VoIP
    ASUS DSL-AX82U - Mesh
    ASUS RT-AC68U - Mesh
    ASUS RT-BE88U Router

    Brother MFC-L2880DW Printer

    I’m on a horse.
  • Operating System
    Windows 11 Pro 25H2 Build 26200.8524
    Computer type
    Laptop
    Manufacturer/Model
    LENOVO Yoga 7 14IRL8 - 7i EVO OLED 14" Touchscreen i5 12 Core 16GB/512GB
    CPU
    Intel Core 12th Gen i5-1240P Processor (1.7 - 4.4GHz)
    Memory
    16GB LPDDR5 RAM
    Graphics card(s)
    Intel Iris Xe Graphics Processor
    Sound Card
    Optimized with Dolby Atmos®
    Screen Resolution
    QHD 2880 x 1800 OLED
    Hard Drives
    M.2 512GB
    Antivirus
    Defender / Malwarebytes
    Other Info
    …still on a horse.
That's very unlikely when MS could just use a registry entry.
 

My Computers

System One System Two

  • OS
    Windows 11 Pro 25H2 26200.8524
    Computer type
    Laptop
    Manufacturer/Model
    Acemagic LX15PRO
    CPU
    AMD Ryzen 7 5825U with Radeon Graphics
    Memory
    16GB
    Screen Resolution
    1920 x 1080
    Hard Drives
    SSD 2TB
    Internet Speed
    30 Mbps
    Browser
    Brave
    Antivirus
    Webroot Secure Anywhere
    Other Info
    System 3

    Acer Swift SF114-34 laptop
    OS Windows 11 Pro 26200.8524
    CPU Pentium Silver N6000
    RAM 4GB
    SSD Samsung 970 EVO Plus SSD 2TB (an upgrade)
  • Operating System
    Windows 11 Pro 23H2 22631.2506
    Computer type
    Laptop
    Manufacturer/Model
    HP Mini 210-1090NR PC (bought in late 2009!)
    CPU
    Atom N450 1.66GHz
    Memory
    2GB
    Browser
    Brave
    Antivirus
    Webroot
I wonder if it is related to two empty folders also called c which are owned by Network Services?

1736332399149.webp
 

My Computers

System One System Two

  • OS
    Windows 11 Pro 25H2 26200.8524
    Computer type
    Laptop
    Manufacturer/Model
    Acemagic LX15PRO
    CPU
    AMD Ryzen 7 5825U with Radeon Graphics
    Memory
    16GB
    Screen Resolution
    1920 x 1080
    Hard Drives
    SSD 2TB
    Internet Speed
    30 Mbps
    Browser
    Brave
    Antivirus
    Webroot Secure Anywhere
    Other Info
    System 3

    Acer Swift SF114-34 laptop
    OS Windows 11 Pro 26200.8524
    CPU Pentium Silver N6000
    RAM 4GB
    SSD Samsung 970 EVO Plus SSD 2TB (an upgrade)
  • Operating System
    Windows 11 Pro 23H2 22631.2506
    Computer type
    Laptop
    Manufacturer/Model
    HP Mini 210-1090NR PC (bought in late 2009!)
    CPU
    Atom N450 1.66GHz
    Memory
    2GB
    Browser
    Brave
    Antivirus
    Webroot
I don't have that 'c' file either in my user\appdata\roaming folder either.
Started the different versions of Windows 11 in my VirtualBox envirenment and no, there is no file c to find.

It must be some app, which some of us use, that left this file.
 

My Computer

System One

  • OS
    Windows 11 Pro 25H2 26200.8457
    Computer type
    PC/Desktop
    Manufacturer/Model
    Build by vendor to my specs
    CPU
    AMD Ryzen 7 5700G
    Motherboard
    MSI PRO B550M-P Gen3
    Memory
    Kingston FURY Beast 2x16GB DIMM DDR4 2666 CL16
    Graphics Card(s)
    MSI GeForce GT 730 2GB LP V1
    Sound Card
    Creative Sound Blaster Audigy FX
    Monitor(s) Displays
    Samsung S24E450F 24"
    Screen Resolution
    1920 x 1080
    Hard Drives
    1. SSD Crucial P5 Plus 500GB PCIe M.2
    2. SSD-SATA Crucial MX500-2TB
    PSU
    Corsair CV650W
    Case
    Cooler Master Silencio S400
    Cooling
    Cooler Master Hyper H412R with Be Quiet Pure Wings 2 PWM BL038 fan
    Keyboard
    Cherry Stream (wired, scissor keys)
    Mouse
    Asus WT465 (wireless)
    Internet Speed
    70 Mbps down / 80 Mbps up
    Browser
    Firefox 130.0
    Antivirus
    F-Secure (Internetprovider version)
    Other Info
    Router: FRITZBox 7490
    Oracle VirtualBox 7 for testing software on Win 10 or 11
I don't have that 'c' file in my user\appdata\roaming folder either.

I decided to do a fresh clean install to start the new year, so my system is about as vanilla as you can get.
 

My Computers

System One System Two

  • OS
    Windows 11 Pro
    Computer type
    Laptop
    Manufacturer/Model
    Dell XPS 16 DA16260
    CPU
    Intel Series 3 Core Ultra X9 388H
    Memory
    64GB LPDDR5x 9600 MT/s
    Graphics Card(s)
    Intel Arc graphics B390 Panther Lake
    Monitor(s) Displays
    16" 3.2K Tandem OLED Infinity Edge
    Screen Resolution
    3200 x 2000 16:10 236 PPI
    Hard Drives
    1 Terabyte M.2 PCIe NVMe SSD
    Case
    Black Anodized Aluminum
    Cooling
    Vapor Chamber Cooling
    Mouse
    None
    Internet Speed
    942 Mbps Netgear Mesh + 2 Satellites
    Browser
    Microsoft Edge (Chromium)
    Antivirus
    Windows Security (Defender)
    Other Info
    NPU delivering 67 TOPS
    Microsoft 365 subscription
    Microsoft OneDrive 1TB Cloud
    Microsoft Visual Studio
    Microsoft Visual Studio Code
    Microsoft Sysinternals Suite
    Microsoft BitLocker
    Microsoft Copilot
    Dell Support Assist
    Dell Command | Update
    Macrium Reflect X subscription
    1Password Password Manager
    Amazon Kindle for PC
    Lightroom/Photoshop subscription
    Interactive Brokers Trader Workstation
  • Operating System
    Windows 11 Pro
    Computer type
    Laptop
    Manufacturer/Model
    Microsoft Surface Laptop 7
    CPU
    Snapdragon® X Elite (12 Core) with Hexagon NPU delivering 45 TOPS
    Memory
    32GB LPDDR5x 8448 MT/s
    Graphics card(s)
    Integrated Adreno GPU
    Sound Card
    Omnisonic speakers with Dolby Atmos spatial sound
    Monitor(s) Displays
    13.8″ PixelSense Flow touchscreen 120 Hz 600 NIT
    Screen Resolution
    2304 × 1536 (201 PPI), 3:2 aspect ratio
    Hard Drives
    1 TB PCIe NVMe Gen 4 SSD
    Case
    Black Anodized Aluminum
    Cooling
    Vapor Chamber Cooling
    Mouse
    None
    Internet Speed
    942 Mbps Netgear Mesh + 2 Satellites
    Browser
    Microsoft Edge (Chromium)
    Antivirus
    Windows Security (Defender)
    Other Info
    Microsoft 365 subscription (Office)
    Microsoft OneDrive 1TB Cloud
    Microsoft Visual Studio 2026
    Microsoft Visual Studio Code
    Interactive Brokers Trader Workstation
    Lightroom/Photoshop subscription
    1Password Password Manager
    Microsoft Sysinternals
    Amazon Kindle for PC
    Microsoft BitLocker
    Microsoft Copilot
I don't have that 'c' file either in my user\appdata\roaming folder either.
Started the different versions of Windows 11 in my VirtualBox envirenment and no, there is no file c to find.

It must be some app, which some of us use, that left this file.

Not sure if I can think of many or any apps that create hidden system files on the root of C Drive, or anywhere.
 

My Computers

System One System Two

  • OS
    Windows 11 Pro 25H2 Build 26200.8524
    Computer type
    PC/Desktop
    Manufacturer/Model
    Sin-built 2013
    CPU
    Intel(R) Core(TM) i7-4770K CPU @ 3.50GHz
    Motherboard
    ASUS ROG Maximus VI Formula
    Memory
    32.0 GB of I forget and the box is in storage.
    Graphics Card(s)
    Gigabyte nVidia GeForce GTX 1660 Super OC 6GB
    Sound Card
    Onboard thingy
    Monitor(s) Displays
    5 x LG 25MS500-B - 1 x 24MK430H-B - 1 x Wacom Pro 22" Touch Screen Tablet
    Screen Resolution
    All over the place
    Hard Drives
    Too many to list.
    OS on Samsung 1TB 870 QVO SATA
    PSU
    Silverstone 1500
    Case
    NZXT Phantom 820 Full-Tower Case
    Cooling
    Noctua NH-D15 Elite Class Dual Tower CPU Cooler / 6 x EziDIY 120mm / 2 x Corsair 140mm somethings / 1 x 140mm Thermaltake something / 2 x 200mm Corsair.
    Keyboard
    Corsair K95 / Logitech diNovo Edge Wireless
    Mouse
    Logitech: G402 / G502 / Mx Masters / Mx Air Cordless
    Internet Speed
    2000/500Mbps
    Browser
    All sorts
    Antivirus
    Kaspersky Premium
    Other Info
    ㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
    TP-Link BE9300 WiFi 7 Bluetooth 5.4 (Archer TBE550E)
    TP-Link TX201 V1 2.5GB Lan

    Grandstream HT812 - VoIP
    ASUS DSL-AX82U - Mesh
    ASUS RT-AC68U - Mesh
    ASUS RT-BE88U Router

    Brother MFC-L2880DW Printer

    I’m on a horse.
  • Operating System
    Windows 11 Pro 25H2 Build 26200.8524
    Computer type
    Laptop
    Manufacturer/Model
    LENOVO Yoga 7 14IRL8 - 7i EVO OLED 14" Touchscreen i5 12 Core 16GB/512GB
    CPU
    Intel Core 12th Gen i5-1240P Processor (1.7 - 4.4GHz)
    Memory
    16GB LPDDR5 RAM
    Graphics card(s)
    Intel Iris Xe Graphics Processor
    Sound Card
    Optimized with Dolby Atmos®
    Screen Resolution
    QHD 2880 x 1800 OLED
    Hard Drives
    M.2 512GB
    Antivirus
    Defender / Malwarebytes
    Other Info
    …still on a horse.
OH, I reread the post. I think I am confusing another thread. I was sure I read that this was only visible when showing hidden system files. my mistake.
 

My Computers

System One System Two

  • OS
    Windows 11 Pro 25H2 Build 26200.8524
    Computer type
    PC/Desktop
    Manufacturer/Model
    Sin-built 2013
    CPU
    Intel(R) Core(TM) i7-4770K CPU @ 3.50GHz
    Motherboard
    ASUS ROG Maximus VI Formula
    Memory
    32.0 GB of I forget and the box is in storage.
    Graphics Card(s)
    Gigabyte nVidia GeForce GTX 1660 Super OC 6GB
    Sound Card
    Onboard thingy
    Monitor(s) Displays
    5 x LG 25MS500-B - 1 x 24MK430H-B - 1 x Wacom Pro 22" Touch Screen Tablet
    Screen Resolution
    All over the place
    Hard Drives
    Too many to list.
    OS on Samsung 1TB 870 QVO SATA
    PSU
    Silverstone 1500
    Case
    NZXT Phantom 820 Full-Tower Case
    Cooling
    Noctua NH-D15 Elite Class Dual Tower CPU Cooler / 6 x EziDIY 120mm / 2 x Corsair 140mm somethings / 1 x 140mm Thermaltake something / 2 x 200mm Corsair.
    Keyboard
    Corsair K95 / Logitech diNovo Edge Wireless
    Mouse
    Logitech: G402 / G502 / Mx Masters / Mx Air Cordless
    Internet Speed
    2000/500Mbps
    Browser
    All sorts
    Antivirus
    Kaspersky Premium
    Other Info
    ㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤㅤ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
    TP-Link BE9300 WiFi 7 Bluetooth 5.4 (Archer TBE550E)
    TP-Link TX201 V1 2.5GB Lan

    Grandstream HT812 - VoIP
    ASUS DSL-AX82U - Mesh
    ASUS RT-AC68U - Mesh
    ASUS RT-BE88U Router

    Brother MFC-L2880DW Printer

    I’m on a horse.
  • Operating System
    Windows 11 Pro 25H2 Build 26200.8524
    Computer type
    Laptop
    Manufacturer/Model
    LENOVO Yoga 7 14IRL8 - 7i EVO OLED 14" Touchscreen i5 12 Core 16GB/512GB
    CPU
    Intel Core 12th Gen i5-1240P Processor (1.7 - 4.4GHz)
    Memory
    16GB LPDDR5 RAM
    Graphics card(s)
    Intel Iris Xe Graphics Processor
    Sound Card
    Optimized with Dolby Atmos®
    Screen Resolution
    QHD 2880 x 1800 OLED
    Hard Drives
    M.2 512GB
    Antivirus
    Defender / Malwarebytes
    Other Info
    …still on a horse.
The one in Roaming is just 1 byte. Mine was created in November 2023, so it's been there a long time.
Have you tried searching your drive for other files with the same modified and/or created date?
 

My Computer

System One

  • OS
    Windows 10/11
    Computer type
    Laptop
    Manufacturer/Model
    Acer
I don't have this file
 

My Computer

System One

  • OS
    Windows 11 Pro 25H2 (RP channel)
    Computer type
    PC/Desktop
    Manufacturer/Model
    MSI
    CPU
    AMD Ryzen 7 9800X3D 8-core
    Motherboard
    MEG X870E Godlike
    Memory
    64GB Corsair Titanium 6000/CL30
    Graphics Card(s)
    MSI Suprim 5080 SOC
    Sound Card
    Soundblaster AE-9
    Monitor(s) Displays
    ASUS TUF Gaming VG289Q
    Screen Resolution
    3840x2160
    Hard Drives
    Samsung 9100 Pro 4TB (gen 5 x4, system drive/games)
    Samsung 990 Pro 2TB
    Samsung 980 Pro 2TB
    Samsung 870 Evo 4TB
    Samsung 870 Evo 2TB
    Samsung T9 4TB
    PSU
    Seasonic PX-2200
    Case
    Bequiet! Dark Base Pro 901
    Cooling
    Noctua NH-D15S Chromax black
    Keyboard
    Logitech G915 X (wired)
    Mouse
    Logitech G903 with PowerPlay charger
    Internet Speed
    900Mb/sec
    Browser
    Microsoft Edge
    Antivirus
    Windows Defender
@Bree (and everyone else) Okay, so here's what I think, now I may be wrong, but I'm pretty sure this is a "marker" file from MS of who's going to get the next features installed whether it be immediately or "down the road" as they describe that some features will be turned off or on for some users who receive this update. I restored a backup of the file that I created a few days ago (trust me, I had this file incredibly protected and locked from attempting to activate should it try). So, as it appears, after the new Cumulative Update for 23H2 (at least for my setup) I haven't received any new features as was described in the OS Build 22635.4660 - since I deleted the "c" file. So, I restored the file and it NOW appears I have all of the new features that are included in this updated build. I believe this file is intended for those who gets the new features as described in the release notes - so leave this file be; as I now have the text located under the icons cut/copy/paste/delete. I think I figured it out, so I'm going to mark this post as RESOLVED.
So if those of us with updated 24H2 systems want the "new features as described in the release notes" but don't have the C marker we should just create the file with the "\" and we'll get them? :-)
 

My Computers

System One System Two

  • OS
    Windows 11 Home, ver 25H2 build 26200.8246
    Computer type
    Laptop
    Manufacturer/Model
    Hewlett-Packard Spectre 13-4001 x360 convertable
    CPU
    Intel Core i5 5200U @ 2.20GH
    Motherboard
    Hewlett-Packard 802D
    Memory
    4 GB
    Graphics Card(s)
    Intel HD Graphics 5500 on board
    Sound Card
    Intel Smart Sound Technology (Intel SST)
    Hard Drives
    Micron 256GB M.2 2280 NGFF SSD MTFDDAV256TBN, (SATA 6.0 Gb/s)
    Keyboard
    Model # G01KB
    Antivirus
    Microsoft Defender
    Other Info
    born on date: 25 Feb 2016
  • Operating System
    Win 11 Home 25H2 build 26200.7922
    Computer type
    PC/Desktop
    Manufacturer/Model
    Asus Desktop model M32AD-US019S (DOM: 6/9/2014 )
    CPU
    Intel Core i7 4th Gen 4790 (3.60GHz), Haswell 22nm Technology, SOCKET 1150
    Motherboard
    H81M-E/M51AD/DP_MB
    Memory
    Samsung 16 GB DDR3 (8GB in 2 modules)
    Graphics card(s)
    NVIDIA GeForce GTX 760, 3GB, and on-board Intel HD Graphics 4600 Rev 6
    Monitor(s) Displays
    HP EliteDisplay E241i LED; HP EliteDisplay E243
    Hard Drives
    Samsung 500GB SSD, 870 EVO (SATA 6.0 )
    Micron 250GB SSD, CT250MX500
    Toshiba HDD, 3GB (original drive w/PC)
    Case
    ASUS
    Keyboard
    ASUS-------------------------
    Antivirus
    MS Defender
    Other Info
    Additional Laptops:

    HEWLETT PACKARD
    HP OmniBook X Flip NGAI (Next Gen AI),
    Model: 16-as0023dx
    PT# B5UH1UA#ABA Product #: B5UH1UA
    delivered and setup 7/25/25
    16" 2K Touch-Screen Laptop
    Intel Core Ultra 7 256V '24 Series 2 - CPU
    Boost Clock Frequency 4.8 gigahertz; Neural Processing Unit (NPU) Yes;
    16GB Memory, LPDDR5X
    1TB SSD PCIe 4.0
    Graphics: Intel Arc 140V
    1 x HDMI 2.1
    1 x Thunderbolt 4
    2K Touch-Screen display, LED, IPS; 1920 x 1200 (Full HD+)
    USB Ports: 1 x USB-C 3.1, 2 x USB-A 3.1
    Wi-Fi 6E
    weight 4.15 pounds

    DELL
    Model:I7591-7483BLK-PUS 2-in-1 (7000 Series)
    purchased 12/3/2019,
    15.6 inch 2-IN-1;
    4K Ultra HD Touch-Screen, 3840 x 2160,
    Intel Core i7 10510U CPU 1.80GHz,
    16GB RAM DDR4 SDRAM 2400 megahert (2 slots),
    dedicated graphics Nvidia GeForce MX250 2 GB Graphics,
    PCIe 512GB Intel SSD + 32GB Optane Memory (Intel Optane Memory H10 with solid-state storage),
    wireless-AX & Bluetooth
    Battery: 68wh, Type 4VGMP 4 cell
So if those of us with updated 24H2 systems want the "new features as described in the release notes" but don't have the C marker we should just create the file with the "\" and we'll get them? :-)
I wouldn't jump to that conclusion. No harm in trying, but I expect nothing will come of it. The file may originate from some, as yet unidentified, third party software.
 

My Computer

System One

  • OS
    Windows 10/11
    Computer type
    Laptop
    Manufacturer/Model
    Acer
I don't see it on any of my PCs or VMs (about 2 dozen in all). Bizarre and mysterious.
--Ed--
 

My Computers

System One System Two

  • OS
    Windows 11
    Computer type
    Laptop
    Manufacturer/Model
    Lenovo X380 Yoga
    CPU
    i7-8650U (8th Gen/Kaby Lake)
    Motherboard
    20LH000MUS (U3E1)
    Memory
    16 GB
    Graphics Card(s)
    Intel UHD Graphics 620
    Sound Card
    Integrated Conexant SmartAudio HD
    Monitor(s) Displays
    FlexView Display
    Screen Resolution
    1920x1080
    Hard Drives
    Toshiba 1 TB PCIe x3 NVMe SSD
    external 5TB Seagate USB-C attached HDD
    PSU
    Lenovo integrated 65W power brick
    Case
    Laptop
    Cooling
    Laptop
    Keyboard
    Integrated Lenovo ThinkPad keyboard
    Mouse
    touchscreen, touchpad
    Internet Speed
    GbE (Spectrum/Charter)
    Browser
    all of em
    Antivirus
    Defender
    Other Info
    Purchased early 2019 as Windows Insider test PC
  • Operating System
    Windows 11
    Computer type
    PC/Desktop
    Manufacturer/Model
    DIY
    CPU
    Ryzen 5800X
    Motherboard
    Asrock B550 Extreme4
    Memory
    128 GB (4x32 DDR5-5600)
    Graphics card(s)
    NVIDIA 3070Ti
    Sound Card
    built-in
    Monitor(s) Displays
    2xDell 2707
    Screen Resolution
    1980x1200
    Hard Drives
    2XNVMe, multiple HDDs from 3 to 12 TB
    PSU
    Seasonic 650
    Case
    NZXT Flo 6
    Cooling
    dual-fan air cooler
    Keyboard
    Logitech Wave
    Mouse
    Logitech Logi
    Internet Speed
    GbE
    Browser
    all of 'em
    Antivirus
    Defender
    Other Info
    temperamental UEFI
Have you tried searching your drive for other files with the same modified and/or created date?
I have now. Two .xml files in C:\Windows\Panther\NewOs\Panther were created on the last modified date for the ...appdata\roaming\c file.

1736370986541.webp

They have identical contents.

Code:
<WINDLP>
<State>0</State>
<TaskCount>0</TaskCount>
<WorkingPath>C:\$Windows.~WS\Sources\Panther</WorkingPath>
<StringCount>0</StringCount>
<DwordCount>0</DwordCount>
<QuadwordCount>0</QuadwordCount>
</WINDLP>
 

My Computers

System One System Two

  • OS
    Windows 11 Home
    Computer type
    Laptop
    Manufacturer/Model
    Acer Aspire 3 A315-23-R9VY
    CPU
    AMD Athlon Silver 3050U
    Memory
    8GB
    Graphics Card(s)
    Radeon Graphics
    Monitor(s) Displays
    laptop screen
    Screen Resolution
    1366x768 native resolution, up to 2560x1440 with Radeon Virtual Super Resolution
    Hard Drives
    1TB Samsung EVO 870 SSD (from April 2026: 250GB EVO 850)
    Internet Speed
    150 Mbps
    Browser
    Edge, Firefox
    Antivirus
    Defender
    Other Info
    fully 'Windows 11 ready' laptop. Windows 10 C: partition migrated from my old unsupported 'main machine' then upgraded to 11. A test migration ran Insider builds for 2 months. When 11 was released on 5th October 2021 it was re-imaged back to 10 and was offered the upgrade in Windows Update on 20th October. Windows Update offered the 22H2 Feature Update on 20th September 2022. It got the 23H2 Feature Update on 4th November 2023 through Windows Update, 24H2 on 3rd October 2024 through Windows Update by setting the Target Release Version for 24H2, and 25H2 on 30th September 2025 through Windows Update by setting the Target Release Version for 25H2.

    UPDATE - 11 April 2026: due to mechanical deterioration this PC has been retired from active duty. The OS with all software and files has been migrated to my System Seven below to carry on as my general purpose 'main machine'.

    My SYSTEM THREE is a Dell Latitude 5410, i7-10610U, 32GB RAM, 512GB NVMe ssd, supported device running Windows 11 Pro.

    My SYSTEM FOUR is a 2-in-1 convertible Lenovo Yoga 11e 20DA, Celeron N2930, 8GB RAM, 256GB ssd. Unsupported device: currently running Win10 Pro, plus Win11 Pro RTM and Insider Dev, Beta, and RP 24H2 as native boot vhdx.

    My SYSTEM FIVE is a Dell Latitude 3190 2-in-1, Pentium Silver N5030, 8GB RAM, 1TB NVMe ssd, supported device running Windows 11 Pro, plus Insider Beta, Dev, and Canary builds (and a few others) as a native boot .vhdx.

    My SYSTEM SIX is a Dell Latitude 5550, Core Ultra 7 165H, 64GB RAM, 1TB NVMe SSD, supported device, Windows 11 Pro 24H2, Hyper-V host machine. Updated to 25H2 on 30th September 2025.

    My SYSTEM SEVEN is a Lenovo Thinkpad T580, Intel Core i7-8650U, 16GB RAM, 512GB NVMe SSD + 2nd 512GB NVMe SSD, a supported device for Windows 11. This is my current general purpose 'main machine'. The installed Windows 11 Home from my System One has been migrated to this machine.
  • Operating System
    Windows 11 Pro
    Computer type
    Laptop
    Manufacturer/Model
    Dell Latitude E4310
    CPU
    Intel® Core™ i5-520M
    Motherboard
    0T6M8G
    Memory
    8GB
    Graphics card(s)
    (integrated graphics) Intel HD Graphics
    Screen Resolution
    1366x768
    Hard Drives
    500GB Crucial MX500 SSD
    Browser
    Firefox, Edge
    Antivirus
    Defender
    Other Info
    unsupported machine: Legacy bios, MBR, TPM 1.2, upgraded from W10 to W11 using W10/W11 hybrid install media workaround. In-place upgrade to 22H2 using ISO and a workaround. Feature Update to 23H2 by manually installing the Enablement Package. In-place upgrade to 24H2 using hybrid 23H2/24H2 install media. Upgraded to 25H2 by Enablement Package. Also running Insider Dev, and Canary builds and Windows 10 as native boot .vhdx.

    My SYSTEM THREE is a Dell Latitude 5410, i7-10610U, 32GB RAM, 512GB NVMe ssd, supported device running Windows 11 Pro.

    My SYSTEM FOUR is a 2-in-1 convertible Lenovo Yoga 11e 20DA, Celeron N2930, 8GB RAM, 256GB ssd. Unsupported device: currently running Win10 Pro, plus Win11 Pro RTM and Insider Dev, Beta, and RP 24H2 as native boot vhdx.

    My SYSTEM FIVE is a Dell Latitude 3190 2-in-1, Pentium Silver N5030, 8GB RAM, 1TB NVMe ssd, supported device running Windows 11 Pro, plus Insider Beta, Dev, and Canary builds (and a few others) as a native boot .vhdx.

    My SYSTEM SIX is a Dell Latitude 5550, Core Ultra 7 165H, 64GB RAM, 1TB NVMe SSD, supported device, Windows 11 Pro 24H2, Hyper-V host machine. Updated to 25H2 on 30th September 2025.

    My SYSTEM SEVEN is a Lenovo Thinkpad T580, Intel Core i7-8650U, 16GB RAM, 512GB NVMe SSD + 2nd 512GB NVMe SSD, a supported device for Windows 11. This is my current general purpose 'main machine'. The installed Windows 11 Home from my System One has been migrated to this machine.
@Bree and others.....So, as I was viewing the same .xml files and the containing folder - It appears to be a setup of of a windows update and media creation tool. I've opened the .xml files, and they all point to Windows store upgrades as well as the main Windows update installations. I've took some screen snippets of the containing text in these files. Please, have a look. So, at this point, I am convinced that this is some type of Windows component update for sure - especially after restoring the original file back (after a crash of course that involved netios.sys which caused a GSOD), I have the newer features immediately available after a reboot that followed the crash. Currently I'm looking for additional logs and perhaps a dump file to verify if that "c" file is part of windows update.
 

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My Computer

System One

  • OS
    Windows 11 Professional 25H2; Linux Mint
    Computer type
    PC/Desktop
    Manufacturer/Model
    Acer
    CPU
    12th Gen Intel(R) Core(TM) i3-1215U 1.20 GHz
    Motherboard
    Acer Aspire C24-1700
    Memory
    16 GB
    Graphics Card(s)
    Video Card: Intel Arc UHD Graphics (Alder Lake-P 282 GT2) - Integrated Graphics Controller [ACER]
    Sound Card
    Intel Alder Lake-P PCH - cAVS (Audio, Voice, Speech)
    Monitor(s) Displays
    Acer [Unknown Model: ACR40B0]
    Screen Resolution
    1920x1080
    Hard Drives
    SSD: WDC PC SN530 SDBPNPZ-512G-1114
    SSD: TEAM TM8PS7512G
    HDD: WDC WD20JDRW-11C7VS0
    HDD: Seagate ST2000LM007-1R8174 HDD: Seagate ST1000LM035-1RK172
    Case
    Acer AIO
    Keyboard
    Razer Ornata V3 X
    Mouse
    Razer Basilisk V3
    Browser
    Brave, Chrome, Firefox, Edge
    Antivirus
    Microsoft Defender
I have now. Two .xml files in C:\Windows\Panther\NewOs\Panther were created on the last modified date for the ...appdata\roaming\c file.
So, I can't find any dump files in the minidump folder or the main windows C:. I did run a windows update log, but I cannot find anything about the C:\Users\<username>\AppData\Roaming directory. However, in the log, you can see when the crash occurred when I restored that "c" file - which was at 9:13 PM. Communications with the WU service seemed to cease at 9:01 PM prior to when I had the crash. The log shows that the WU service did not reinitialize until 9:27 PM, which was when I discovered that the new features were available shortly thereafter. May be just coincidence, however, I can't seem to link the modification dates of those xml files to my restored "c" file on my PC as I was messing around with darn file for quite a few days, and when I restored it, it changed the modified date of the file to the current date and time which was yesterday. The .xml files have a modification date of 1/5/25 1:56 PM. So, maybe we're back to square one again about the origin of the file, I'm thinking?
 

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My Computer

System One

  • OS
    Windows 11 Professional 25H2; Linux Mint
    Computer type
    PC/Desktop
    Manufacturer/Model
    Acer
    CPU
    12th Gen Intel(R) Core(TM) i3-1215U 1.20 GHz
    Motherboard
    Acer Aspire C24-1700
    Memory
    16 GB
    Graphics Card(s)
    Video Card: Intel Arc UHD Graphics (Alder Lake-P 282 GT2) - Integrated Graphics Controller [ACER]
    Sound Card
    Intel Alder Lake-P PCH - cAVS (Audio, Voice, Speech)
    Monitor(s) Displays
    Acer [Unknown Model: ACR40B0]
    Screen Resolution
    1920x1080
    Hard Drives
    SSD: WDC PC SN530 SDBPNPZ-512G-1114
    SSD: TEAM TM8PS7512G
    HDD: WDC WD20JDRW-11C7VS0
    HDD: Seagate ST2000LM007-1R8174 HDD: Seagate ST1000LM035-1RK172
    Case
    Acer AIO
    Keyboard
    Razer Ornata V3 X
    Mouse
    Razer Basilisk V3
    Browser
    Brave, Chrome, Firefox, Edge
    Antivirus
    Microsoft Defender

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