Forum bricked during attempted upgrade- HTTP 500 error

radhq

Cancel request - working with chatGPT I was able to fix the issue:

Diagnosed a broken mid-upgrade composer state ✅

Fixed missing vendor files ✅

Cleared cache ✅

Identified and disabled a bad extension ✅

Navigated phpMyAdmin like a boss ✅

Cleaned up the database ✅

Completed the upgrade ✅

clarkwinkelmann

radhq is the problem fixed?

If you still need help, please share the exact error message from the log file.

Please also share which commands you already ran to try to fix the issue, so we know what you tried. If the problem is already fixed, this information could help other users who find this discussion in the future.

While AI is a great tool, it has often provided out of date instructions for Flarum, so it's a good idea to write down which instructions actually worked.

radhq

clarkwinkelmann

It seems to be working, going through and checking extensions now.

I was pretty naive and just hit the upgrade button without looking into it. It failed halfway though and then started returning a 500 server error.

✅ Your forum is trying to load a file:
/vendor/symfony/polyfill-php72/bootstrap.php

❌ But that file is missing because the upgrade failed midway.

The missing file causes PHP to crash → gives you the 500 error.
The good news:
You can fix this without reinstalling everything.
You just need to properly rebuild the vendor/ folder using Composer.

Here’s how to fix it (step-by-step):
In your Terminal (you're already in the right folder: public_html/radhq/forum),
type this:

bash
Copy
Edit
composer install --no-dev
and press Enter.

✅ This will rebuild all your missing files based on your composer.lock file.

Then:
Once that finishes, clear Flarum's cache.

That worked and I was now able to see the flarum page asking for the database password. When I entered in the password I got an error related to an outdated SEO extension. So we changed the name of extension and now it works.