Microsoft Edge not accepting installation of Add-Ons

Hi there
I hope I can get some assistance here, since the Microsoft Answers website has been replaced by one where it seems one only has to deal with an AI assistant, which keeps suggesting the same solutions that do not work. I have found the new MS support website totally frustrating to use, even at other times.

My Lenovo IdeaPad 5 Pro 14ACN6 notebook, has Win 11 Pro, ALL available Windows Updates installed, with AMD Ryzen 7 5800U, 16GB RAM, all Lenovo drivers/software up-to-date. A few weeks ago, while trying to start Windscribe VPN add-on, which I have used for years and which I have installed on 2 other notebooks and never failed to work, I unexpectedly got an error it was corrupted and tried to re-install it. This went on for too long ending up in failure. Later I discovered other add-ons could also not get installed I have working on other notebooks like Adblockers failing.

I went to the new MS Support Forum learn.microsoft.com and posted the issue in detail => at this link. (not sure the correct link has been posted at it seemed to get truncated in this editor). May be it can be googled & has title: "MS Edge windows closes shortly after starting, repair function/sfc scannow not helping"
The AI assistant suggested a whole list of possible solutions and steps to solve the issue, ranging from clearing browser data, sfc /scannow & DISM, repairing Edge via app => modify, manually installing Edge over existing installation, etc.
After a few days, the problem became more serious I think after trying out some of the suggested resolution steps, with Edge just briefly starting and then disappearing without fully loading, so I practically had no functioning browser.
I have added comments to the post, mentioning the steps did not help BUT keep getting the same nonsensical suggestions in response seconds later.

• ALL the suggested solutions from MS Learn website AI robot DO NOT HELP
• Repair of MS Edge via Apps => Modify did not help repair Edge and MS Edge keeps closing soon after start.
• Installing Edge over existing app did not help
• Using Windows back-up image brings me to 3 weeks ago when MS Edge was working BUT I could NOT install ANY add-ons
• Windows 11, version 25H2 (repair version) does NOT repair the MS Edge to allow installing add-ons, both from Chrome & Microsoft stores.

So I am stuck at this point. I normally use that Windscribe VPN add-on, but even more important adblockers like Adguard, Adblock Plus & Adblocker Ultimate, which I emphasize work on 2 other notebooks & I have used for years, also in Firefox.

What can I do to correct this, something the above steps, including a repair Windows installation does not seem to solve?
A search for solutions elsewhere brings up suggestions like those I mentioned and at that link mentioned above, which I request being looked at before responding.

Thank you in advance

Export your bookmarks to a file. Make note of your installed extensions. Make record of your saved passwords unless you have other record of them elsewhere. The following procedure deletes them so you will have to reinstall extensions and import your bookmarks back in.
Co-pilot gives very detailed info on how to deal with this. Use it or not as I am just passsing it on.

COPIED AND PASTED FROM CO-PILOT:
You’ve already gone through all the standard fixes (SFC, DISM, Edge repair, reinstalling Edge, even a Windows repair install), and the fact that none of them helped is actually the key to the problem. When Edge refuses to install any extensions — Microsoft Store or Chrome Store — and especially when it starts closing shortly after launch, the root cause is almost always corruption inside the Edge profile or its extension policy store, not the OS itself.

Windows repair installs do not reset any of the components that usually break in this scenario.

Below are the fixes that actually resolve this specific failure pattern.

1. Rebuild the Edge profile (most reliable fix)​

Close Edge completely using task manager, then rename this folder:

Browse to:
%LOCALAPPDATA%\Microsoft\Edge\User Data
Rename it to: User Data.old

Launch Edge again — it will create a fresh profile.This resets the extension database, Secure Preferences, service workers, and all cached extension data.

This step alone fixes the majority of cases like this.

2. Remove any leftover Edge extension policies​

Even if you never set policies, an empty or orphaned policy key will block all extension installs.

Check and delete these keys if they exist:

HKLM\SOFTWARE\Policies\Microsoft\Edge\ExtensionInstallBlocklist<br>HKLM\SOFTWARE\Policies\Microsoft\Edge\ExtensionInstallAllowlist<br>HKCU\SOFTWARE\Policies\Microsoft\Edge\ExtensionInstallBlocklist<br>HKCU\SOFTWARE\Policies\Microsoft\Edge\ExtensionInstallAllowlist
If any of these keys exist — even blank — Edge treats them as active policy.

3. Delete the “Secure Preferences” file​

Inside your Edge profile:
%LOCALAPPDATA%\Microsoft\Edge\User Data\Default\Secure Preferences
If this file is corrupted, Edge will reject extension installs and may crash shortly after launch.Delete it — Edge will recreate it automatically.

4. Clear broken extension service workers​

Go to:
%LOCALAPPDATA%\Microsoft\Edge\User Data\Default\Service Worker
Delete everything inside.A corrupted service worker can block all new extension installs.

5. Remove leftover extension folders​

Check:

%LOCALAPPDATA%\Microsoft\Edge\User Data\Default\Extensions
If you see folders for extensions you no longer have installed, delete them.

6. Verify no extension policies are set in Group Policy​

Open: gpedit.msc

Navigate to:
Computer Configuration → Administrative Templates → Windows Components → Microsoft Edge → Extensions
Make sure everything here is Not configured, especially:

• Allow extensions
• Control which extensions cannot be installed
• Control which extensions are installed silently

Why the repair install didn’t fix it​

Because Windows repair does not touch:

• Edge profiles
• Edge extension databases
• Secure Preferences
• Extension policies
• Service worker caches

So the underlying corruption survives the repair.

Hi there
Thank you very much for the detailed response. It is refreshing knowing one is not dealing with a robot to help solve an urgent issue.
Here is a summary of what I did:

1. Step one successfully carried out, with new profile created, having to complete customization. I need to note though, that the bookmarks reappeared and the saved passwords, at least when I tried to access a site, the login data was offered, meaning they were not deleted(?).
   When I restarted Edge however, I could not install Adguard adblocker or Windscribe VPN add-on, both ending in:
   "There was an error installing the extension. Click "Get extension" to try again" or one saying there was an error installing and that I should try to refresh the page and try again.
2. I hope I did this right, but when I went to Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft, the folder "Edge" was not listed (no idea whether that is normal), so I could not see, nor delete any of those keys.
3. In C:\Users\username\AppData\Local\Microsoft\Edge\User Data\Default, a folder "Secure Preferences" is not there nor a visible file, BUT when I typed in those 2 words in search, it finds a 35.9kb file, which I guess could be what was meant & deleted it.
4. Done
5. In C:\Users\username\AppData\Local\Microsoft\Edge\User Data\Default, I see no folder "Extensions", but Extension Rules, Extension Scripts & Extension State. Not sure that was meant, but I deleted them ...
6. "Allow Extensions" was already set to "Not configured", but I could not see the other 2 ... Control which extensions cannot be installed & Control which extensions are installed silently

After that, I started Edge, but unfortunately, when I tried to install Adguard Adblocker or Malwarebytes Browser Guard, both ended with:
"An error has occurred
There was a problem adding the item to Microsoft Edge. Please refresh the page and try again".

I think you can help me identify where I could have gone wrong or misunderstood the instructions as I am not conversant with some PC stuff.

Thank you for taking your time.

Kind regards