Hi @NT_Frank,
This may be related to the APC opcode cache, as mentioned in a few old threads; if you’re running that, try disabling it (at least temporarily) to see if it resolves the problem.
OCS has not been replaced by OJS and OMP, but it hasn’t been maintained actively for a while. See this blog post (and note that the timeline proposed there is quite out of date).
Regards,
Alec Smecher
Public Knowledge Project Team