Commenting on this issue, because MC-12485 was marked as a duplicate. Bug still exists with 1.5.1 - it now occurs almost every other time somebody uses a nether portal, i.e. when somebody uses a nether portal there seems to be about a 50% chance that the server will crash! It might be that it occurs whenever the nether is left using a portal.
Commenting on this issue, because MC-12485 was marked as a duplicate.
Bug still exists with 1.5.1 - it now occurs almost every other time somebody uses a nether portal, i.e. when somebody uses a nether portal there seems to be about a 50% chance that the server will crash!
It might be that it occurs whenever the nether is left using a portal.