@ Edgar
The “Registration has been disabled.” message would not be coming from Connections so I can’t really help with what might be displaying it and how to fix it.
As for the non-writable cache directory … Sounds like maybe server level software was updated? HAve you triple checked the path of the cache folder to make sure you were working with the correct folder? Should be this:
../wp-content/plugins/connections/cache/
If none of those suggestions worked from the FAQ, unfortunately you’ll have to contact your webhost and ask them what needs to be done to make a folder writable. The suggestions I give a very standard so they must have some type of security policy in place that is preventing it from being writable.
Sorry I can not be more of a help … but I hope it helps at least a little!
