Firefox doesn't work with Windows Vista Extended Kernel

[TechActivate 78]

Hi guys

I recently wanted to try using Windows Vista. I first installed the 2 updates (KB4474419 and KB971512), then installed the extended kernel and the mfplatsetup, then did the osver.ini stuff (worked as winver reported 6.1.7601). I then proceeded to install Firefox 102.4.0 ESR. The installer did not launch, however I just extracted it via 7-zip. After installing it, I tried to launch it, however it failed with this error:

Is there any way to fix this?
Thanks

 

[Vistaar]

Welcome to the forum TechActivate 78. First of all, please be aware that the extended kernel was not a Microsoft product: It was a developer’s project (i.e. a hack) of dubious legality, and it is no longer being developed (the latest version is a year old). It has now gone out of fashion for two reasons: (1) It no longer supports the latest browser versions that now require Windows 10 or 11, and (2) Its developer has lately been working on a fork of open-source Chromium known as Supermium that actually supports vanilla (unmodified) Vista and even XP. I don’t think this forum has any active member who uses the extended kernel anymore, and we never had very many.

I first installed the 2 updates (KB4474419 and
KB971512)...

You mean those were the only updates applied to a fresh installation of Vista SP2!? True, Windows Update doesn’t work anymore, and KB4474419 is said to be required by the extended kernel. KB971512 was an important Platform Update component, but not the entire Platform Update! I’m not going to write about how to get Vista “fully patched” to April 2017 in March 2024, especially since other members usually feel compelled to do so. I’m not sure if this is important, since his mfplatsetup replaces Vista components with Windows 7 Platform Update components IIRC, but here’s a list of Vista’s Platform Update components for future reference:

KB960362
KB971512
KB971513
KB971514
KB2117917 (Supplement)

I then proceeded to install Firefox 102.4.0 ESR.

The last version of Firefox to support Windows 7 and 8 is actually 115 ESR:

Firefox users on Windows 7, 8 and 8.1 moving to Extended Support Release | Firefox Help

Security updates will end in six months. It is said to work with the extended kernel. Here’s a post at MSFN that offers some advice (however you have already tried most of the things mentioned):

[WIP] Windows Vista Extended Kernel

 

[TechActivate 78]

Alright, thanks. I had seen Supermium and also Silverfox, so I'll try those.
Thanks

 

[Vistaar]

Alright, thanks. I had seen Supermium and also Silverfox, so I'll try those.
Thanks

Silverfox is just a theme that would make Firefox look like 12-year-old Chrome.

 

[wither 3]

As noted in another thread, I've been using Supermium for about three weeks now in a non-extended version of Vista x64 Home Premium. Works well although loading some websites is slow.