Intermittent white screens caused by PHP-FPM being turned on?

[maestroc]

I am just asking this to see if anyone knows what might be the cause of this. A site I work on recently started going up and down with completely blank white screens on all pages. Wait a few seconds, reload, and it would then come up fine. My uptime monitor said this was happening all day long. Turning on error reporting, etc. showed nothing. The page was still blank even with reporting on.

The problem was not due to an htaccess issue (I swapped it out with the default version). On a whim I went into WHM and turned off the PHP-FPM switch for that one account. Suddenly the problem stopped. The site now loads normally every single time.

Any ideas what could cause such a thing? It isn't a huge problem to have FPM off on that account but I am wondering what might be the root cause? Other accounts on that same server do not have this problem even though they are essentially copies of each other.

[Per Yngve Berg]

Examine the server logs. This is a server set-up problem and not a Joomla issue.

What user have you configured PHP-FPM to run as and is that user the owner of the site files?

[Webdongle]

https://forumpostassistant.github.io/docs/ please. With and without PHP-FPM

[Slackervaara]

I remember that earlier I often got white screen. It was an PHP error and caused by timeout because the process stopped after 30 seconds and gave white screen. If you have cpanel you might be able to increase the timeout to a longer time.

[AMurray]

perhaps you need to also set "display_errors" to "On", it is sort of the companion setting to "error_reporting".

I think without display errors on, you get PHP errors only logged to the file and not displayed on screen.