My serial number for CS6 is invalid?

Nobody here can help with that. You’ll need to contact Adobe directly for help with it.

I am experiencing the same problem.  My purchased CS6 Master Suite product box is less than a year old, but all of a sudden it is saying my serial number is invalid.  I would call Adobe customer support if I could find a phone number...

I have exactly the same problem! And where can I find the telefon number?

I'm having the same problem. It started with the September 17 update to Acrobat. I've done the chat help and phone help with Adobe, and they are all oblivious to the issue. The only really helpful erson I got was the new guy taking Creative Cloud orders, and he tried his best to sort it out, but ran into a wall as well. The chat help said I needed to contact the re-seller I purchased CS6 Master Collection from, which still does't answer the question about why I have had a legitimate copy of CS6 on my laptop for over two years, my serial numbers are listed on my Adobe account, and now all of a sudden I'm back in the 30 day trial mode. The phone help people said I needed to resolve it with chat help. One big, vicious circle.