Sorry to re-open an old topic, but I'm facing the same problem, and was able to reproduce: Fatal Error Zend OPcache cannot allocate buffer for interned strings.
For me it's happening after I changed the VM memory size (vmWare Workstation v15). I'm using latest pfSense 2.4.4 Patch 3 out-of-the-box, just downloaded and installed with default options - ZFS, no disk encryption, no RAID.
If I set the VM to 256MB, the system boots normally, I can use web configuration, etc.
But if I power off and change the memory size to 2GB, it gives the error above, and the menus are all unusable. The only option that works is 8 - Shell. Going back to 256MB allows me to boot again.
Screenshots here
Interestingly, using 2.5.0-DEV branch (built Jul 24 21:30:13 EDT 2019) doesn't present the same problems. I can change the memory size back without any problems.