Aapt.exe finished with non-zero exit value 1

I cannot build an android solution now. Any clue what this is about?!

FAILURE: Build failed with an exception.

• What went wrong: Execution failed for task ':processDebugResources'.

com.android.ide.common.process.ProcessException: org.gradle.process.internal.ExecException: Proces

In my case the problem was, that there were filenames in my assets folder that had invalid characters.

• Filenames can’t be too long.

• äöüß… don’t seem to be allowed

• Spaces seem to be allowed (!)

Also, after making changes to the filenames in src/assets, search your project for assets folder, and delete all it’s content (except for the main asset folder src/assets), because these are not cleaned when you recompile!!!

After changing these filenames (and deleting the files with invalid names in the other (cached) folders (android,…)), the build worked again!!