Ignore the post that you may have seen as he had no clue and misinformation. ''<p>James Formalwear [[#question-1489638|said]]</p>'' <blockquote>I need assistance downloading Firefox on a Windows Server 2003 R2. I saw online that since it is a older system I am able to download an older versión of Firefox. </blockquote> Windows Server 2003 R2 is based on NT 5.2 which is same as Windows XP https://en.wikipedia.org/wiki/Windows_NT The most recent version you can run on the ancient Windows Server 2003 R2 and WinXP was the old Firefox 52.9.0esr (32-bit) released back on June 26, 2018. Firefox 53.0 and later (till Fx 115 ESR) required Windows 7, Windows Server 2008 or later. See below for Firefox Setup 52.9.0esr.exe https://archive.mozilla.org/pub/firefox/releases/52.9.0esr/win32/en-US/ or if you prefer another language locale then see the folders at https://archive.mozilla.org/pub/firefox/releases/52.9.0esr/win32/ The Win64 (64-bit) version requires Windows 7 or later to run. Keep in mind that Firefox 52.9.0esr is very behind on security vulnerabilities patches since.