If your site is experiencing issues that you think might be related to PHP issues, here’s how you turn on error reporting in WordPress:
Find line one below in wp-config.php, comment it out, and add the rest below. This is meant to be done on a development site, in a local environment.
https://gist.github.com/spigotdesign/098fbaae4731a75cb354
WordPress will now start logging errors in debug.log file within /wp-content directory.
Even if you don’t notice major errors with your site you can still often find warnings on deprecated code or other PHP issues.