Game crashes when a map tries to update new chunks

When using a map, the client crashes (with a message of internal server error) as soon as a new chunk is being updated on a map. If we remain in areas where the previously created map does not have to update new chunks, all is OK, but as soon as we load a new chunk, the crash happens. It then becomes impossible to login into the game unless the player data is erased, which is certainly not desirable.