Debug certificate expired
Once a year you see very starnge error in your android project:
Error generating final archive: Debug certificate expired on …
To fix it on Linux or OS X:
rm -f ~/.android/debug.keystore
Then run Project-> Clean in APDE.
On Windows file debug.keystore should be in folder %USERHOME%/.android, can’t verify it. Find it and delete, then clean project in APDE as described.