Android update 17 seems incompatible with external Jars

Same thing happened to me but my folder was labeled "lib" instead of "libs" arg! updating was a little rough this time around... fixed after removing the external jars from the project settings and changing the folder to libs

crash at run time with exceptions that look like this: Could not find class 'javax.mail.internet.InternetAddress', referenced from method com.my.project.Main.isValidEmailAddress

If you have problems with external jars, then:

1. create a folder named libs.
2. Copy and paste all needed external jar files into that folder.

It will automatically be included, as explained on this page: Dealing with dependencies in Android projects