After click on play on the launcher window a new tab occurs with the title "game output (username)". Launcher log creates Error information mentioned in Summary line and game wont start. In my case the problem was a corrupted geforce driver installation, which was only noticeable in combination with minecraft, since nowere a bad driver status was provided (nvidia control panel, device manager etc.). A manual reinstallation of the latest driver software solved the problem. I`m not sure wheather the exit code relate to a grafic card driver problem, but for me it helped.