A compilation error such as error generating final archive: Debug certificate expired on occurs because the debugging key of the new Android SDK has a one-year trial period, if this problem occurs after the android SDK of your computer is installed for one year, you only need to delete the early key file, the default key file of the system is displayed in the preferences> Android => build menu of the eclipse Window menu, Where default debug keystore is displayed. For example, the Windows XP system currently in use may be c: \ Documents ents and Settings \ User Name \. android \ debug. keystore, you only need to delete debug. the keystore file is ready. The eclipse ADT plug-in will automatically generate a debugging version at the next compilation. The key validity period is still one year, but do not forget to delete the old version of the program on your phone, otherwise, a message such as re-installation failed due to different application signatures is displayed.