"map ff_xxxx missing, disconnecting"
 

i have sv_allowupload, and sv_allowdownload both set to 1 and i still get that error when trying to connect to my server when its on custom maps.

Perhaps you already have a map downloaded that doesn't match the map on the server?

nope, i dont

and ur thinking of the error

"you map xxxx dosent match the servers, disconnecting"

Do you use sv_downloadurl? If so, make sure that the access rights of the files on the web server are set correctly.

Maybe check your client setting
cl_allowdownload "1"

If you have this in your server.cfg:
Get rid of it or change it so it works as it should. As pizza already said, if the link is linking to a existing link, which doesn't has the custom maps on it.. It'll disconnect. I had the same thing yesterday.