This error manifests itself when using Malwarebytes Browser Guard and Firefox releases post v128.0.3, ie v129.0 and later.
https://support.malwarebytes.com/hc/en-us/articles/4410269415443-Duplicate-blocks-in-Firefox-with-Desktop-Security-for-Window-s-integration-with-Browser-Guard
It happens attempting to login to a site & after hitting the 'Log In' button, nothing happens.
Malwarebytes are working on a fix.
Work around -
https://support.malwarebytes.com/hc/en-us/articles/4410269415443-Duplicate-blocks-in-Firefox-with-Desktop-Security-for-Window-s-integration-with-Browser-Guard
It happens attempting to login to a site & after hitting the 'Log In' button, nothing happens.
Malwarebytes are working on a fix.
Work around -
- Uninstall the MBG addon from Firefox; or,
- Use an alternative browser - I've confirmed this - by using MS Edge with the addon installed.
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My Computer
At a glance
Windows 11 Pro 25H2 (Build 26300.9445)Intel Core Ultra 9 285 5.6 GHz32.00 GBIntel Integrated Graphics (128 MB)
- OS
- Windows 11 Pro 25H2 (Build 26300.9445)
- Computer type
- PC/Desktop
- Manufacturer/Model
- Dell Pro Max Tower T2 FCT2250
- CPU
- Intel Core Ultra 9 285 5.6 GHz
- Motherboard
- 64-bit operating system, x64-based processor
- Memory
- 32.00 GB
- Graphics Card(s)
- Intel Integrated Graphics (128 MB)
- Sound Card
- Realtek Audio
- Monitor(s) Displays
- Dell P2714H Monitor
- Screen Resolution
- 1920 x 1080
- Hard Drives
- 1 x 512GB M.2 XG10d SED KIOXIA PCIe solid state drive (Internal)
1 x 2TB Seagate ST2000DM008-2UB102 HDD (Internal)
1 x 4TB Seagate STGX4000400 External HDD
1 x 6TB WD Elements AE 2689 External HDD
- PSU
- 500 Watts
- Cooling
- Air
- Keyboard
- Microsoft Wired Keyboard 600
- Mouse
- Microsoft USB Basic Optical Mouse v2.0
- Browser
- Firefox
- Antivirus
- Windows Defender + Malwarebytes Premium
- Other Info
- BaseBoard Manufacturer Dell Inc.
BaseBoard Product 022RY57
BaseBoard Version A01





