Hello @notok123,
Internal server errors (error 500) are often caused by plugin or theme function conflicts, so if you have access to your Dashboard, try deactivating all plugins. If you don’t have access to your Dashboard, try manually resetting your plugins (no Dashboard access required). If that resolves the issue, reactivate each one individually until you find the cause.
If that does not resolve the issue, try switching to the Twenty Seventeen theme to rule-out a theme-specific issue. If you don’t have access to your Dashboard, access your server via SFTP or FTP, or a file manager in your hosting account’s control panel (consult your hosting provider’s documentation for specifics on these), navigate to /wp-content/themes/ and rename the directory of your currently active theme. This will force the default theme to activate and hopefully rule-out a theme-specific issue.
If that does not resolve the issue, it’s possible that a .htaccess rule could be the source of the problem. To check for this, access your server via SFTP or FTP, or a file manager in your hosting account’s control panel, and rename the .htaccess file. If you can’t find a .htaccess file, make sure that you have set your SFTP or FTP client to view invisible files.
If you weren’t able to resolve the issue by either resetting your plugins and theme or renaming your .htaccess file, we may be able to help, but we’ll need a more detailed error message. Internal server errors are usually described in more detail in the server error log. If you have access to your server error log, generate the error again, note the date and time, then immediately check your server error log for any errors that occurred during that specific time period. If you don’t have access to your server error log, ask your hosting provider to look for you.
Besides all the above, have a look at this thread where another user had the same issue:
https://www.ads-software.com/support/topic/error-500-after-updating-to-wordpress-5-0/
And this article with a very clear tutorial:
https://www.wpbeginner.com/wp-tutorials/how-to-fix-the-internal-server-error-in-wordpress/
If you still have issues to solve your problem, I’d recommend you to get in contact with the support team of your hosting, they should be able to restore your website to the last backup ??
And in case you need a developer to fix it, you can publish your offer here:
https://jobs.wordpress.net/
Hope all of that helps! ??
