Iit’s an internal error that is not handled properly. They don’t want to tell you the exact error message and detailed information around that, because it would expose the internal state of the backend and that would be a security issue. There is really nothing more that they can tell you, except that a developer needs to look at this (and possibly thousands to tens or hundreds of thousands of similar logged errors) and they probably already are.
Are you not rotating your logs with for example logrotate?