I have a Sugar Enterprise 9.0 instance that was created from a Sugar Cloud backup and has been running locally in a vagrant box on my PC for the last several months with no problems. Today I started getting a blank white page and an error 500 when trying to open this instance. As far as I know, a blank white page implies a PHP error somewhere. There were no changes made to it (that I know of) between the last time I logged into it successfully about two weeks ago and now. Restarting vagrant and restarting the PC did not help. The sugarcrm.log file shows no errors. There are also no obvious errors in /var/log/syslog. I can ssh into the vagrant box, and I can access the database in PHPStorm. What else can I try to troubleshoot this, short of deleting this instance and creating a new one from a cloud backup?