title: Error: Gradle: execution failed for task ':app:preDexDebug'
body: <p>I had a self created jar from another projected imported as a library into my other project. When I changed code in that project and exported a new jar to replaced the old one I cannot run my app anymore. I only get the following error:</p>
  
  <p><img src="https://i.stack.imgur.com/uU7pu.png" alt="enter image description here"></p>
  
  <p>I have tried removing and adding and adding as dependency, adding as library. Nothing seems to work. I have also done clean build and a rebuild. </p>