Dashboard not working properly after upgrade to version 3
I recently upgraded my self-hosted Vanilla Forums installation from 2.4 to v2021.009 (using this guide https://success.vanillaforums.com/kb/articles/158-upgrading-self-hosted-vanilla to delete obsolete files and directories).
Unfortunately, while the forum itself is working, the administration UI (Dashboard) isn't working at all. Most Links in the left-hand menu render this page (shown in the screenshot) which seems to be a messed-up version of the category configuration screen. The URL in the browser is correct, but it always renders this category management page.
Looking into the error log, the only thing I can find is this message:
[error] 204970#204970: *13517 FastCGI sent in stderr: "PHP message: PHP Warning: No custom theme provider found! in /data/forum/library/Vanilla/Theme/ThemeService.php on line 523" while reading response header from upstream, client: ***, server: ***, request: "GET /api/v2/themes/R_Noise?revisionID= HTTP/1.1", upstream: "fastcgi://unix:/run/php/php7.4-fpm.sock:", host: "***", referrer: "***"
Since the settings page is visibly scrambled, it could be related as the error message complains about the absence of a
I'd appreciate any help in fixing this issue.
Thanks in advance!