Create PHP Error Logs
Edit the wp-config.php file
Add this to your wp-config.php file. This file can be edited via FTP and is located at the root of your website folder.
Add the log file
You'll need to create a file within wp-content of your site directory. The name should match what you added to your wp-config.php file above, i.e. "phperrorlogs.log" in the example.
Now PHP errors will be logged to that file for your troubleshooting needs.