I use Eclipse for develop android apps, but when run projects see this error:
Installation failed due to invalid APK file!
In my case this was caused by errors in a .jar file included my library. The .jar file was one I created and so I was able to fix it. Here is a breakdown of how the problem started and how I fixed it:
to fix it:
Having included all the files that were not part of the src folder caused a few duplicates in the project and .jar:
This caused the .apk to be invalid. Hope this helps someone. NOTE: this solution will only work if you have library files that you have changed and compiled yourself and have made the same mistake as I did when I included folders that were not needed.