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Can't install FF on newly upgraded Windows 11 - incompatibility error message

j.canham-clyne
j.canham-clyne
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Bought a new computer that was supposed to come with Windows 11, but came with Windows 10 and right to upgrade. Set up computer, downloaded Firefox, and it ran fine. after a couple of hours, ran the upgrade to Windows 11. Firefox stopped opening. uninstalled then reinstalled Firefox several times, but each time during installation get the following message (image below):

"C:\WINDOWS\SYSTEM32\MSVCP140.DLL is either not designed to run on Windows or it contains an error. Try installing the program again using the original installation media or contact your system administrator or the software vendor for support. Error status 0xc000012f."

Have tried installing with and without defaults, and refreshing instead of reinstalling.

Bought a new computer that was supposed to come with Windows 11, but came with Windows 10 and right to upgrade. Set up computer, downloaded Firefox, and it ran fine. after a couple of hours, ran the upgrade to Windows 11. Firefox stopped opening. uninstalled then reinstalled Firefox several times, but each time during installation get the following message (image below): "C:\WINDOWS\SYSTEM32\MSVCP140.DLL is either not designed to run on Windows or it contains an error. Try installing the program again using the original installation media or contact your system administrator or the software vendor for support. Error status 0xc000012f." Have tried installing with and without defaults, and refreshing instead of reinstalling.
Attached screenshots

All Replies (2)

jscher2000 - Support Volunteer
jscher2000 - Support Volunteer
  • Top 10 Contributor
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Hmm, that file should come with Windows. Possibly one of your other applications replaced it with an older version? To refresh the Visual C++ DLL files, you can (re)run Microsoft's installer for the VC Runtime files:

(A) Open https://docs.microsoft.com/en-US/cpp/windows/latest-supported-vc-redist?view=msvc-160#visual-studio-2015-2017-2019-and-2022

(B) In the "Visual Studio 2015, 2017, 2019, and 2022" section of the article, download the installer for your system:

  • 64-bit Windows: the "X64" download
  • 32-bit Windows: the "X86" download

(C) Run that installer and restart Windows.

Can Firefox install now?

j.canham-clyne
j.canham-clyne Question owner
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Five reboots for other updates and a bit of "BIOS Self-Healing" later, yes! Thank you so much!