Thank you so much Tim. And yes mod_sec is enabled will ask our hosting to whitelist the location.
Just thought I'd add this since I just ran into it. I kept getting this error this morning on one of the sites we were working on. I was really getting annoyed because it was working before. Then I did a browser inspect and realized specific files weren't getting loaded and it was crashing. I gave it a half hour after purging my cache and everything. I did notice at the time the site was also running slow. This error message will come up randomly if the site is struggling. I think my host was having issues at the time so I just waited a half hour and everything started working again. Some times it's not actually Moodle at all, it's a server issue that you have no control over.