FPM handler is hiding exception details, blank screen

[shadowhand]

Description:

Our system had a check that was throwing an exception early on in application bootstrapping. This exception caused the FPM handler (v3) to display the "white screen of death" with an HTTP 500 error.

I tried to set display_errors=On, display_startup_errors=On in php/conf.d/php.ini but this had no impact; the white screen remained.

How to reproduce:

Set the HANDLER=throws.php with content:

<?php

require __DIR__ . '/vendor/autoload.php';

throw new Exception('Bref hides this exception');