“Conversion to Dalvik format failed with error 1” on external JAR

Question

In my Android application in Eclipse I get the following error.

UNEXPECTED TOP-LEVEL EXCEPTION:
java.lang.IllegalArgumentException: already add

Answer 1

This can also be caused if you have added Android.jar file to your build path, perhaps by an accidental quick fix in Eclipse. Remove it with right clicking Project -> build path -> configure build path -> android.jar, remove.