This message is triggered when an internal Corona error occurs during rendering. Aside from regular Internal Error message, this one also informs you that Corona has failed to save render elements. You can still manually save render elements from the Corona VFB.
See:
Solutions:
To make sure this bug is fixed in the future, please report this error at https://support.chaos.com/hc/en-us/requests/new, and try to provide as much information as possible, ideally including the scene where this error is reproducible.
You can still manually save render elements from the Corona VFB - see links above.