Are you running in Windows 8 / Vista Compatibility Mode with the browser that you used and got that error message?

Server 2008 equates to Windows 7. https://www.microsoft.com/en-us/cloud-platform/windows-server-2008 Same end of support date as Windows 7.

No, i was actually trying to install via IE from Mozilla's site. After unpacking the install file, the attached error message popped up, then i was redirected to the sys requirements page for Firefox 60.x

The user agent that shows in the System Details list is 32-bit Firefox 52 on 64-bit Windows Vista (NT 6.0).

User Agent: Mozilla/5.0 (Windows NT 6.0; WOW64; rv:52.0) Gecko/20100101 Firefox/52.0

Its a Windows 2008 Server, not Vista

If you open a command window (cmd.exe) and run ver what version does Windows report?

• 6.0.x => treated like Vista
• 6.1.x => treated like Windows 7

If your Firefox is misreporting the version as 6.0 when it should be 6.1, clear the Compatibility settings of your Firefox shortcut (right-click > Properties > Compatibility) and any custom user agent string (How to reset the default user agent on Firefox).

You are mistaken

Windows 2008 with service pack 2 which is Vista based will be supported until.

Main support ended in 2015 while extended support will be ended in 2020.

This is directly from Microsoft's website.

Windows Server 2008 Service Pack 2 2009-04-29 2015-01-13 2020-01-14

I don't understand why Mozilla is dropping support for a currently supported product.

https://support.microsoft.com/en-ca/lifecycle/search/1163

If you open a command window (cmd.exe) and run ver what version does Windows report?

   6.0.x => treated like Vista
   6.1.x => treated like Windows 7 

If your Firefox is misreporting the version as 6.0 when it should be 6.1, clear the Compatibility settings of your Firefox shortcut (right-click > Properties > Compatibility) and any custom user agent string (How to reset the default user agent on Firefox).

Hi nikm2, support forum volunteers do not set policy, nor do we always have time to run web searches to research "why" questions. This decision went into effect with the release of Firefox 52 in March 2017; it's done; it is what it is.

Firefox is open source software, so you and other Windows 2008 "R1" users can arrange for it to be modified and recompiled to run on Vista-based Windows if you like.

Support for Windows XP and Vista has been dropped as of 53.0 and later so that will especially include the server 2008 version that is based on Vista.

Two years ago the number of WinXP users using Firefox were nine times that of Vista.

Mozilla is not going to put back support for Vista in current Releases nor extend support for 52 ESR now just for a small number of users using the EOL Vista or the 2008 Server based on Vista.