Hey,
maybe you can do a posting in Meta - ownCloud Central explaining why you have chosen the “Server-Apps” category which is about additional apps installed on your ownCloud for a problem with the ownCloud server? I think this could help the ownCloud team to improve the forums category description so that the correct categories are chosen.
For your problem itself you could have used the forums search like:
https://central.owncloud.org/search?q=explode()%20expects%20parameter%202%20
to find an existing thread for this message: