Did the 8.3 replace official repo 8.2 or does it use different naming for php binaries? The config files might be separate too.
Try using phpinfo() to check your working config. You can just place a file with the function in the root of your webserver and it should work.
It seems like the memory allowance is too low for drupal to load.
Ngl I was convinced for a good while it’s mostly a result of smoking near them.