Windows 10 reached EOS (end of support) on October 14, 2025. If you are on Windows 10, see this article.

Avatar for Username

Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More
Open

Windows ExtensionSettings registry key takes priority over ExtensionSettings REG_SZ/REG_MULTI_SZ

Firefox for Enterprise Extensions
Mike Kaply replied
Matt
Matt

We are managing Firefox settings using Intune via Imported ADMX templates.

We are managing Extension Settings via 'Extension Management (JSON on one line)' which works fine for our force installs, force removals etc.

We have noticed that some users have installed 3rd party extensions which create the ExtensionSettings key in the registry with the 3rd party extension details.

The issue we see if when ExtensionSettings exists as a REG_SZ or REG_MULTI_SZ under `HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Mozilla\Firefox` it is then ignored if the `HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Mozilla\Firefox\ExtensionSettings` key exists.

Is there a setting we can use to have these settings merged by Firefox or have the REG_SZ/REG_MULTI_SZ take priority or is the only way to ensure enterprise policy continues to work we need to migrate our extension settings into the key rather than string?

Thanks!

We are managing Firefox settings using Intune via Imported ADMX templates. We are managing Extension Settings via 'Extension Management (JSON on one line)' which works fine for our force installs, force removals etc. We have noticed that some users have installed 3rd party extensions which create the ExtensionSettings key in the registry with the 3rd party extension details. The issue we see if when ExtensionSettings exists as a REG_SZ or REG_MULTI_SZ under `HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Mozilla\Firefox` it is then ignored if the `HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Mozilla\Firefox\ExtensionSettings` key exists. Is there a setting we can use to have these settings merged by Firefox or have the REG_SZ/REG_MULTI_SZ take priority or is the only way to ensure enterprise policy continues to work we need to migrate our extension settings into the key rather than string? Thanks!

All Replies (4)

Mike Kaply
Mike Kaply
  • Moderator
Mozilla Staff

Are you saying there are multiple ExtensionSettings keys? I didn't know that was possible.

Can you post a screenshot of what your registry looks like?

Matt
Matt Question owner

Sorry, for the confusion I am saying I can have ExtensionSettings configured as a string (REG_SZ) in the Firefox key and every thing works fine.

There is a 3rd party extension which is being installed and is creating ExtensionSettings as a key under Firefox which then means the configured ExtensionSettings string (REG_SZ) is ignored when Firefox loads the policies.

I've attached images of the registry and Firefox about:policies before the ExtensionSettings key is present and then after the key is present.

If I need to convert the ExtensionSettings string (REG_SZ) into the key then I can do that, but I am looking to see if there is either a way for Firefox to merge the key and string to avoid doing that.

Mike Kaply
Mike Kaply
  • Moderator
Mozilla Staff

OK that's a new one. ExtensionSettings should not be a be key that has extension IDs underneath it. What they are doing is not documented at all (and I'm surprised it works).

I'm not sure if I should ignore the keys underneath or try to combine them.

I'll figure out something.

Mike Kaply
Mike Kaply
  • Moderator
Mozilla Staff

I've opened https://bugzilla.mozilla.org/show_bug.cgi?id=2048696

Ask a question

You must log in to your account to reply to posts. Please start a new question, if you do not have an account yet.