DatastoreFailureException: Internal Error Exception Messages

On rare occasions, an application may spawn errors similar to the below: 
    internal error.
at     (
at$1.convertException     (

As the exception message suggests, this log indicates that the datastore encountered an internal error while handling the datastore operation. Unfortunately, there’s nothing that a developer can do to fix this error since it’s an internal App Engine issue.

Generally this type of exception fixes itself sooner or later; if it persists, file an issue at the App Engine bug tracker: