Android packaging failure: invalid filename

Symptoms

• When building to Android, a message like the following is displayed in the console (where FILENAME is the name of your Project):
  

  CommandInvokationFailure: Android Asset Packaging Tool failed. See the Console for details. 

• Stderr[
  <FILENAME>: error: Invalid filename. Unable to add.
  ]

Cause

There is a known limitation in the Android Asset Packaging Tool meaning that filenames of Assets cannot exceed 100 characters.

Files that have a name longer than 100 characters will fail the invocation of the Android Asset Packaging Tool.

Resolution

Rename all the offending files so their filenames are under 100 characters.

You can see a list of all files causing this error message in the console.