Please your answer is not clear, I have the same error message when I tried to update the app list after putting the new app module in addon directory, I think this is something code error on the app.
I think this is because of when we creating a module(The Folder Name). the module name should not contain space, insted of space you can use underscore.
i found my error , there is space in the name of module , i remove it and it's work