Question

After updating to the latest developer tools, ADT 14, my Android project that includes library projects will no longer run producing the error:

Dx UNEXPECTED TOP-LEVEL EXCEPTION: ... already added: ...
...
Conversion to Dalvik format failed with error 1

The other threads describing this issue with solutions that include removing and re-adding the projects do not work.

Answer 1

This problem is listed as a known issue of ADT 14. Here’s the quote from the Android Tools Project Site:

Project not building with error
[2011-10-20 23:32:04 - MyApp] Dx UNEXPECTED TOP-LEVEL EXCEPTION:<class>: already added: <class>
This is due to a failure to remove previous library source folders from the
main project. Incidentally, the fragility around those linked source
folders is one of the reason we are moving away from this mechanism
(see more info at
http://tools.android.com/recent/buildchangesinrevision14). The
solution is to remove those <libraryname>_src source folders from
your projects. Just right click them and choose Build Path > Remove
from Build Path. You should also be prompted to remove the linked
folder which you should do. If you’re not prompted, remove it
manually. You can see some screenshot of the problem in this great
post:
http://android.foxykeep.com/dev/fix-the-conversion-to-dalvik-format-failed-with-error-1-with-adt-14

Solution:

As it says, the solution is to remove the <libraryname>_src source folders from your projects. You can do this by right clicking them and choose “Build Path -> Remove from Build Path” or in your project properties (Java Build Path -> Source tab).