Villagers spontaneously becoming zombie villagers and escaping

I have moved this report to the appropriate project, Minecraft (Bedrock codebase). Please note that the BDS project is only for bugs in the custom server software.

Is it possible that your villagers were converted by a lightning strike? This can happen if the ceiling/roof is less than 3 blocks above them; see MCPE-9943. It could also explain there being additional zombie villagers in the lake, if there were previous villagers there who were struck by another lightning bolt.

Come to think of it, the game converts villagers to zombie villagers by deleting the villager entity and spawning the zombie villager in its place. Natural spawning randomly displaces the spawned entity from the target block, so if lightning struck them, some of your villagers nearest the walls might have spawned outside the enclosure rather than having escaped it. Is that a reasonable explanation for how they came to be outside?

Edit: Don't know what I was thinking. Lightning changes villagers into witches, not zombie villagers.

Affects 1.10 pocket as well. I have come accross this bug twice in two different worlds.

The first was a multiplayer world. We have two desert villages near are base. All of the buildings and surrounding areas are well lit. Suddenly overnight, one of the two villages was empty, except for a single zombie villager in a house (who was also strangely passive). There was no sign of a zombie raid happening.

The second was in my singleplayer world. I have a villager breeder and a trading hall, once again all well lit. About half of the villagers suddenly are missing or have been converted to zombies, and one even somehow escaped, though no blocks were broken. These villagers were completely inaccessible to zombies, so I have no idea how so many villagers spontaneously converted to zombies.

I just had this happen in a well established village on Xbox (version where the foxes came, can’t remember the number). Fortunately, the villager turned in a house where it was alone.

After looking over this report again, I think it is just incredible. The OP observed

• villagers missing from minecarts in a sealed room

• zombie villagers in the room, numbering about half the number of missing villagers

• no zombie in the room

• a roughly equal number of zombie villagers in a nearby lake

The most likely explanation is that

• The room was not adequately lit. (We get a lot of reports saying monsters spawn in "well lit" areas, where it turns out the light level calculations have not been understood or done correctly; see MCPE-302.)

• A zombie villager spawned and attacked the villagers, killing half and converting half to zombie villagers. (This would be the expected proportion for normal difficulty.)

• The zombie villagers in the nearby lake just spawned randomly and wandered into the lake by chance. (Zombie villagers accumulating in lakes along with drowned is a known issue; see MCPE-34032 and MCPE-62030.)

@unknown's and @unknown's reported cases can be explained similarly. Possibly there are two additional factors:

• random villager despawnings (MCPE-21416)

• zombie villagers spawning in an unlit area then walking into the lit area after targeting a villager (Zombie villagers can target villagers at a distance of 35 blocks.)

I had this happen in Bedrock.  Iron farm with 20 villagers in a 5x5 area completely closed off, no way in or out.  Jack o lantern in the middle of the 5x5.  Had no problem for days, then while I was in the vicinity digging a tunnel for a new railline, they turned into zombies.

Is it possible that the edge of the 5x5 was in the radius for monsters to spawn but the lightsource wasn't?  So while I was digging the railline, the edge of the 5x5 was within mob spawn radius, but the light in the middle wasn't, and the system saw that edge as being unlit?