If this was a real bug, your forum would be unusable. The above error probably happened while the class was locked for writing at the same time a user needed to access it. You might be able to reduce the frequency of this issue with a longer-lived Zend Opcache revalidate_freq, perhaps 5 seconds.
In my opinion this is a bug in Zend Opcache:
- When revalidating a file that is currently locked for writing, Zend Opcache executes the partially written file, or it treats the file as though it does not exist. A better solution would be to use the cached version of the file in that case and defer the revalidation.