Just experienced this for myself, I built a villager breeder(image attached) with no way for zombies to get in, and had 3 villagers in it, and then afked at my nearby AFK fisher. Came back a few hours later, and all three were gone and there was somehow a Husk inside...
PS. I checked the light levels of every block inside, none were 7 or darker, so a Husk should not have even been able to spawn... I have no idea what is happening here...
EDIT: checked my server's console, i did not get the error the OP was describing... seems like there are quite a few causes for this.
Just experienced this for myself, I built a villager breeder(image attached) with no way for zombies to get in, and had 3 villagers in it, and then afked at my nearby AFK fisher. Came back a few hours later, and all three were gone and there was somehow a Husk inside...
PS. I checked the light levels of every block inside, none were 7 or darker, so a Husk should not have even been able to spawn... I have no idea what is happening here...
EDIT: checked my server's console, i did not get the error the OP was describing... seems like there are quite a few causes for this.
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