Corrupted database - eM client doesn ́t start

After upgrade to version 3 I can ́t start eM client. Only shows some message about corrupted database. Have you some idease what to do?

can you please paste here the text of the error message so we can analyze it?

I don’t get the corrupted database message… in my case, the emclient agent is asking for an activation key that I don’t have (I’m using the free version). Thanks.