I have built several mods successfully, but now all of a sudden I get the following popup error whenever I attempt to build a mod: "Invalid data when building asset bundle".  It doesn't matter what content is in the mod, and I get the same error whenever I try to build anything.  The only thing I think may have changed between it working and not working is maybe an update to Unity.  I am not sure if the Ibn Battuta update is a factor.  I have built mods that were initialized before the update, but maybe not ones that were initiatlized after.  

The error in the console says this:  DirectoryNotFoundException: Could not find a part of the path.  It then goes on to show a very long path.

I've tried using the debug tool and reimporting the project, but that didn't solve the problem.