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