This has happened twice now. Long distance teleports into ungenerated chunks causes the server to completely crash and require a forced shutdown/restart after 60s without any tick updates. Server continues to crash again when that account reconnects at the problem location. 2 fixes have worked, 1) walk/fly another account separate from the issue account over to the location of the teleport, this in turn generates the chunks and server proceeds working properly. 2) After the second crash, at a much further distance, it was discovered setting network-compression-threshold=256 to -1 (to disable) allowed the account to connect properly and allow the server the opportunity to get past the specific issue causing the crash. When the second crash happened we teleported a different user to the same coordinates (without the first account connected) and this also caused the server to crash on a completely different system. Leaving network-compression-threshold disabled caused several other issues (rendering/porting/others...) and needed to be re enabled back to 256.For the time being we are no longer allowing long range teleports.
Note : not specifically repeatable as other teleports have not caused the error, however in the 2 specific crash points both occured with the teleport.