1406149 - Can't set Firefox as the default browser on Windows 10 if the account is created after Firefox was installed

Status: NEW

(Firefox :: Installer, defect, P3)

Description

[(no longer active)]

Steps to reproduce:

- Have one account where Firefox is installed and set to default.
- From Control Panel, User Accounts, Managed accounts, create a new account without a Microsoft account, without administrative privileges
- Log in to the new account and run Firefox.
- When Firefox prompts to be the default browser, say yes.
- In the Windows dialog that is opened, Firefox isn't listed.

This was reproducible on Windows 10 Home.

Comment 1

[Molly Howell (she/her) (mostly inactive)]

Was Firefox installed with administrator privileges? If not, then this is expected and there's not really any way around it. Otherwise, this sounds like an installer bug.

Comment 2

[(no longer active)]

Yes the original account did have admin privileges.

Comment 3

[Molly Howell (she/her) (mostly inactive)]

Probably an installer bug then.

Unfortunately this doesn't reproduce for me, which means I have to ask you for the contents of some paths in this machine's registry. Can you export any of the following keys that exist (I expect only one of them will, I just don't know which one) and attach them here?

HKEY_LOCAL_MACHINE\SOFTWARE\Clients\StartMenuInternet\[anything starting with Firefox]

And from both the account that installed Firefox and the newly created account:
HKEY_CURRENT_USER\SOFTWARE\Clients\StartMenuInternet\[anything starting with Firefox]

Thanks.

Comment 4

[(no longer active)]

Attachment: HKEY_LOCAL_MACHINE\SOFTWARE\Clients\StartMenuInternet\FIREFOX.EXE

Comment 5

[(no longer active)]

Attachment: HKEY_CURRENT_USER\SOFTWARE\Clients\StartMenuInternet\FIREFOX.EXE (admin account)

Comment 6

[(no longer active)]

Attachment: HKEY_CURRENT_USER\SOFTWARE\Clients\StartMenuInternet\Firefox-E7CF176E110C211B (non-admin account)

Note that the key wasn't named FIREFOX.EXE here!

Comment 7

[Molly Howell (she/her) (mostly inactive)]

Thanks.

So I did not expect all of those keys to exist. Especially the one in the non-admin account surprises me; I think the bug is that that key is there. Specifically, I think it's being created during updates when we should be recognizing the one in HKLM and just letting that one work instead (or, if we absolutely must create that key, we also need to make the related file type entries in HKCR).

I have a few more questions to check my theory:
1) Was a Firefox update run from the non-admin account?
2) Does the registry key HKEY_CLASSES_ROOT\FirefoxHTML-E7CF176E110C211B exist in the non-admin account?
3) If you delete HKEY_CURRENT_USER\SOFTWARE\Clients\StartMenuInternet\Firefox-E7CF176E110C211B does Firefox then appear in the default browser list?

Comment 8

[(no longer active)]

(In reply to Matt Howell [:mhowell] from comment #7)
> I have a few more questions to check my theory:
> 1) Was a Firefox update run from the non-admin account?

I can't be 100% sure (this isn't my own computer) but my strong suspicion is yes.

> 2) Does the registry key HKEY_CLASSES_ROOT\FirefoxHTML-E7CF176E110C211B
> exist in the non-admin account?

Yes.

> 3) If you delete
> HKEY_CURRENT_USER\SOFTWARE\Clients\StartMenuInternet\Firefox-
> E7CF176E110C211B does Firefox then appear in the default browser list?

No.  When I delete this key, and attempt to make Firefox the default browser, the key is recreated automatically again...

Comment 9

[Molly Howell (she/her) (mostly inactive)]

Okay, that makes this a bit different situation from what I thought. I'll have to do some more investigating.