Error 500 out of nowhere on self-hosted

[Matthew Hawkins]

My website has been working fine for many months, and now I suddenly have a 500 error and cannot start the site. The uploads/logs folder is empty, no errors from anytime recently. 

 

The most recent change was caching being disabled (moving from redis to no caching, and the constants.php was updated) but the website continued to work fine after that until today.

 

My Ubuntu VPS details are current in my customer profile.

[Randy Calvert]

A 500 error indicates some sort of server error. Have you checked your server’s Apache/PHP error logs?

[Matthew Hawkins]

1 hour ago, Randy Calvert said:

A 500 error indicates some sort of server error. Have you checked your server’s Apache/PHP error logs?

No errors that I can see. Have updated now from PHP 7.3 to 7.4, but made no difference. Site doesn't even start - can't access admin panel, even in recovery mode.

[teraßyte]

Did you change anything else on the server before the PHP version change? Did something else update automatically maybe?

[David N.]

Because the 500 errors are server errors, you should contact your host and ask them to help. 

[Marc Stridgen]

You have "connection refused" showing up there, which would indicate there is an issue with connecting to your database

[Tennman]

I would check permissions on all the folders, and the files in the root folder, especially the conf_global.php and .htaccess files. Wrong permissions will throw a 500 Internal Server error.