After you install the Android SDK in Eclipse, it generates a debug signing certificate for you in a keystore called debug.keystore. The Eclipse plug-in uses this certificate to sign each application build that is generated.
Now, the problem with this debug certificate is that it is only valid for a year, or 365 days. If your Eclipse IDE uses an expired debug certificate, you will not be able to create and/or deploy an Android app.
To fix this problem all you need to do is delete the debug.keystore file.
- Go to Preferences
- Default debug keystore
There you should see the folder where the file is located. Simply delete that file and you are good to go.