problem subscribing to forums

I’ve been away for a long time and returned to an updated site & very nice it is to.

As I stopped getting updates I’m guessing that during the upgarde some member settings were lost such as subscriptions to individual forums.

My problem is that when I try to resubscribe I get a pop up telling me I was “unsuccessful” and asking that I try again. This goes round in a loop.

Any suggestions as to how I can overcome this would be most appreciated.