Windows 10 reached EOS (end of support) on October 14, 2025. If you are on Windows 10, see this article.

Søg i Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Læs mere

Local theme "corrupt"

Best regards,

At the beginning of 2025, I created a private theme and installed it locally (Windows 10), consisting of a manifest.json and a GIF file. It worked perfectly. Now, on Windows 11, I'm trying to use the theme again, but when I upload the file (.zip or .xpi — via about:addons -> Install Add-on From File), I always get the message that the file is corrupted. However, if I test it temporarily under about:debugging, it works immediately without any issues.

I would really appreciate a solution! <3

Best regards, At the beginning of 2025, I created a private theme and installed it locally (Windows 10), consisting of a manifest.json and a GIF file. It worked perfectly. Now, on Windows 11, I'm trying to use the theme again, but when I upload the file (.zip or .xpi — via about:addons -> Install Add-on From File), I always get the message that the file is corrupted. However, if I test it temporarily under about:debugging, it works immediately without any issues. I would really appreciate a solution! <3

Alle svar (3)

Hi

I recommend that you ask about this on the official add-ons forum at:

https://discourse.mozilla.org/c/add-ons/35

Paul said

Hi I recommend that you ask about this on the official add-ons forum at: https://discourse.mozilla.org/c/add-ons/35

Thank you, I've opened a post there and hope for support! ♥

As a general comment, you cannot install unsigned extensions/themes on the standard release of Firefox. Perhaps you were using the Extended Support Release or Developer Edition on your other computer?