Shocking news! Expired residence permit can cause problems. Even inside European Union.
In previous part I had problems with Tallinn city officials. I tried to register my living address. Landlords signature was not valid because he had taken a home loan from bank. City database says apartment owner was bank.
Bank sent letter of attorney to landlord. This letter gave him permission to sign a paper. This paper gave me permission to fill a form. With this form I was able to register my address in Estonia. After registering living address I could renew my residence permit.
Problem was all this took three weeks. During this time my residence permit ended. Not a biggie.