Issue: in_array() expects parameter 2 to be array, null given

I take it the VaultWiki 4 install was an upgrade from 4.0.0 RC 2 or something like that, that was perhaps disabled for a while? It's the only way I can see this array index possibly not being in the cache. I can fix this in the future by not bundling the cache validation into one check. It will be a little slower, but it would make sure every new field was always in there.

For now, you should be able to force it to update by disabling VW_CACHE_ON in vault/config.php, visiting one of the wiki pages with the error, then turning the cache back on.

No, I installed VW4.0.7 without installing a lower version of VW.

Well I can't see how you would get a cache entry containing one of the index fields and not the rest, unless there was an old cache entry lying around from days past. From what I can see they are all populated at the same time. Even if one of the values is corrupted, it always sets a default value.

I suppose it doesn't matter where the entry came from. At this point it is gone, and the future fix I proposed above would take care of it again regardless how it appeared (by validating each field individually at runtime).