For those needing access to worlds which have been disabled by this bug while we await a patch, I have found several quick fixes, they all work on the same principle; that you have a moment to teleport far from the area before the entity begins any pathfinding. As soon as your game loads, teleport to a location known to be far from this entity. The position of the entity is included in the crash report, so just refer to this position and teleport at least a few hundred blocks away. This has worked for me in every case thus far, so hopefully it works for at least most of you, provided that the entity was not within the permanently loaded spawn chunks - (but even if that is the case, one would just need to involve an extra step of temporarily changing the world spawn location via /setworldspawn - just change it temporarily to the same distant position you teleported to) Once you have safely teleported away from the entity, and you are no longer crashing, you have several options: 1.) If the area doesn't matter, but the mob does - just avoid the area until this issue is patched. but this is difficult, as this crash can get you from many chunks away, and it does not matter which player wanders into the zone of death, all players will crash. 2.) If you need the area to be accessible, and the mob does not matter much to you, what you want to do is place a repeating command block within the spawn chunks, and issue the command " /execute at @p run kill entity @e[type=bee, distance=0..10] " (presuming it is a bee, edit mob type according to your crash report) and then refer to your crash report for the entity's location. With this command block active within the spawn chunks, bravely teleport yourself directly to the location of the problem entity via /tp X Y Z. The speed of the command block issuing the order to kill the problem entity is fast enough to kill the entity before it can fire off any pathfinding. I've witnessed the deaths of many poor bees and parrots in this manner over the past few days. Make sure to destroy your command block when done, or you will continue to autokill all bees/parrots/whatever within 10 blocks of you as you travel throughout your world, like some sort of reaper of flying mobs.
Congrats, you have now quick fixed your world until the next bee or parrot tries to fly into a fence post. Hope this is helpful to anyone feeling locked out of their worlds due to this bug.
Jephyrr
For those needing access to worlds which have been disabled by this bug while we await a patch, I have found several quick fixes, they all work on the same principle; that you have a moment to teleport far from the area before the entity begins any pathfinding. As soon as your game loads, teleport to a location known to be far from this entity. The position of the entity is included in the crash report, so just refer to this position and teleport at least a few hundred blocks away. This has worked for me in every case thus far, so hopefully it works for at least most of you, provided that the entity was not within the permanently loaded spawn chunks - (but even if that is the case, one would just need to involve an extra step of temporarily changing the world spawn location via /setworldspawn - just change it temporarily to the same distant position you teleported to)
Once you have safely teleported away from the entity, and you are no longer crashing, you have several options:
1.) If the area doesn't matter, but the mob does - just avoid the area until this issue is patched. but this is difficult, as this crash can get you from many chunks away, and it does not matter which player wanders into the zone of death, all players will crash.
2.) If you need the area to be accessible, and the mob does not matter much to you, what you want to do is place a repeating command block within the spawn chunks, and issue the command " /execute at @p run kill entity @e[type=bee, distance=0..10] " (presuming it is a bee, edit mob type according to your crash report) and then refer to your crash report for the entity's location. With this command block active within the spawn chunks, bravely teleport yourself directly to the location of the problem entity via /tp X Y Z. The speed of the command block issuing the order to kill the problem entity is fast enough to kill the entity before it can fire off any pathfinding. I've witnessed the deaths of many poor bees and parrots in this manner over the past few days. Make sure to destroy your command block when done, or you will continue to autokill all bees/parrots/whatever within 10 blocks of you as you travel throughout your world, like some sort of reaper of flying mobs.
Congrats, you have now quick fixed your world until the next bee or parrot tries to fly into a fence post. Hope this is helpful to anyone feeling locked out of their worlds due to this bug.