--- a/net/minecraft/world/entity/monster/EntityZombieVillager.java
+++ b/net/minecraft/world/entity/monster/EntityZombieVillager.java
@@ -49,6 +49,13 @@
 import net.minecraft.world.level.gameevent.GameEvent;
 import org.apache.logging.log4j.Logger;
 
+// CraftBukkit start
+import net.minecraft.server.MinecraftServer;
+import org.bukkit.entity.ZombieVillager;
+import org.bukkit.event.entity.CreatureSpawnEvent;
+import org.bukkit.event.entity.EntityTransformEvent;
+// CraftBukkit end
+
 public class EntityZombieVillager extends EntityZombie implements VillagerDataHolder {
 
     public static final DataWatcherObject<Boolean> DATA_CONVERTING_ID = DataWatcher.a(EntityZombieVillager.class, DataWatcherRegistry.BOOLEAN);
@@ -62,6 +69,7 @@
     private NBTBase gossips;
     private NBTTagCompound tradeOffers;
     private int villagerXp;
+    private int lastTick = MinecraftServer.currentTick; // CraftBukkit - add field
 
     public EntityZombieVillager(EntityTypes<? extends EntityZombieVillager> entitytypes, World world) {
         super(entitytypes, world);
@@ -78,7 +86,7 @@
     @Override
     public void saveData(NBTTagCompound nbttagcompound) {
         super.saveData(nbttagcompound);
-        DataResult dataresult = VillagerData.CODEC.encodeStart(DynamicOpsNBT.INSTANCE, this.getVillagerData());
+        DataResult<NBTBase> dataresult = VillagerData.CODEC.encodeStart(DynamicOpsNBT.INSTANCE, this.getVillagerData()); // CraftBukkit - decompile error
         Logger logger = EntityZombieVillager.LOGGER;
 
         Objects.requireNonNull(logger);
@@ -134,6 +142,10 @@
     public void tick() {
         if (!this.level.isClientSide && this.isAlive() && this.isConverting()) {
             int i = this.getConversionProgress();
+            // CraftBukkit start - Use wall time instead of ticks for villager conversion
+            int elapsedTicks = MinecraftServer.currentTick - this.lastTick;
+            i *= elapsedTicks;
+            // CraftBukkit end
 
             this.villagerConversionTime -= i;
             if (this.villagerConversionTime <= 0) {
@@ -142,6 +154,7 @@
         }
 
         super.tick();
+        this.lastTick = MinecraftServer.currentTick; // CraftBukkit
     }
 
     @Override
@@ -186,8 +199,11 @@
         this.conversionStarter = uuid;
         this.villagerConversionTime = i;
         this.getDataWatcher().set(EntityZombieVillager.DATA_CONVERTING_ID, true);
-        this.removeEffect(MobEffects.WEAKNESS);
-        this.addEffect(new MobEffect(MobEffects.DAMAGE_BOOST, i, Math.min(this.level.getDifficulty().a() - 1, 0)));
+        // CraftBukkit start
+        this.setPersistenceRequired(true); // CraftBukkit - SPIGOT-4684 update persistence
+        this.removeEffect(MobEffects.WEAKNESS, org.bukkit.event.entity.EntityPotionEffectEvent.Cause.CONVERSION);
+        this.addEffect(new MobEffect(MobEffects.DAMAGE_BOOST, i, Math.min(this.level.getDifficulty().a() - 1, 0)), org.bukkit.event.entity.EntityPotionEffectEvent.Cause.CONVERSION);
+        // CraftBukkit end
         this.level.broadcastEntityEffect(this, (byte) 16);
     }
 
@@ -204,7 +220,13 @@
     }
 
     private void c(WorldServer worldserver) {
-        EntityVillager entityvillager = (EntityVillager) this.a(EntityTypes.VILLAGER, false);
+        // CraftBukkit start
+        EntityVillager entityvillager = (EntityVillager) this.a(EntityTypes.VILLAGER, false, EntityTransformEvent.TransformReason.CURED, CreatureSpawnEvent.SpawnReason.CURED);
+        if (entityvillager == null) {
+            ((ZombieVillager) getBukkitEntity()).setConversionTime(-1); // SPIGOT-5208: End conversion to stop event spam
+            return;
+        }
+        // CraftBukkit end
         EnumItemSlot[] aenumitemslot = EnumItemSlot.values();
         int i = aenumitemslot.length;
 
@@ -219,7 +241,9 @@
                     double d0 = (double) this.e(enumitemslot);
 
                     if (d0 > 1.0D) {
+                        this.forceDrops = true; // CraftBukkit
                         this.b(itemstack);
+                        this.forceDrops = false; // CraftBukkit
                     }
                 }
             }
@@ -245,7 +269,7 @@
             }
         }
 
-        entityvillager.addEffect(new MobEffect(MobEffects.CONFUSION, 200, 0));
+        entityvillager.addEffect(new MobEffect(MobEffects.CONFUSION, 200, 0), org.bukkit.event.entity.EntityPotionEffectEvent.Cause.CONVERSION); // CraftBukkit
         if (!this.isSilent()) {
             worldserver.a((EntityHuman) null, 1027, this.getChunkCoordinates(), 0);
         }