XF 1.5 forum returning 403 error all of a sudden?


One of my forums that has been working fine until a couple of days ago is all of a sudden giving a 403 error.

All other forums work, nothing has changed on the server side, and this forum has worked without a hitch for months so I don't know what changed. Any suggestions?


Sorry, maybe it's not a 403, I get the error:

You don't have permission to access /forum/index.php on this server.

And, like I said, there are 20+ other forums that work fine so it seems odd.


XenForo moderator
Staff member
ou don't have permission to access /forum/index.php on this server.
That is a server issue typically due to something like mod security.

Contact your host and they will be able to resolve it for you.


Yes, I've seen that reply on other similar posts... but if nothing has changed how would it all of a sudden stop working?

I'm on a dedicated machine and the index.php url never changes, only the argument changes so I don't understand how mod_security would affect it, and more importantly why it would not affect it for months and then all of a sudden be an issue. Can you elaborate so I can do a better job of approaching the right person about this?