ADT needs to update but find no update

Question

Today I installed API8 from the SDK manager, previously I only had been working with API14. After the SDK manager was done, and upon restarting ADT I got this error:

Answer 1

I tried all methods mentioned here, but still without success. What finally helped was the tip from No repository found error in Installing ADT in eclipse Indigo:

Uncheck “Contact all update sites during install to find required software”