Describe the bug
As soon as I walked in the 1rst floor, the server crashed and I am unable to log in anymore without crashing the server.

To Reproduce
Things needed to reproduce the behavior:

1. Minecraft Version 1.18.1 & Forge 39.0.79
2. The version of the mod you are using: 1.18.1-2.0.2
3. If you are using any datapacks/self-created loot-tables etc: NO
4. Server or Singleplayer: MULTIPLAYER
5. OS: Windows 10

Expected behavior
Being able to explore the tower

Console log

[11:58:26] [Server thread/ERROR]: Encountered an unexpected exception
net.minecraft.ReportedException: Ticking block entity
at net.minecraft.server.MinecraftServer.m_5703_(MinecraftServer.java:872) ~[server-1.18.1-20211210.034407-srg.jar%2378!/:?]
at net.minecraft.server.dedicated.DedicatedServer.m_5703_(DedicatedServer.java:328) ~[server-1.18.1-20211210.034407-srg.jar%2378!/:?]
at net.minecraft.server.MinecraftServer.m_5705_(MinecraftServer.java:808) ~[server-1.18.1-20211210.034407-srg.jar%2378!/:?]
at net.minecraft.server.MinecraftServer.m_130011_(MinecraftServer.java:668) ~[server-1.18.1-20211210.034407-srg.jar%2378!/:?]
at net.minecraft.server.MinecraftServer.m_177918_(MinecraftServer.java:258) ~[server-1.18.1-20211210.034407-srg.jar%2378!/:?]
at java.lang.Thread.run(Thread.java:833) [?:?]
Caused by: java.lang.NoSuchMethodError: 'boolean net.minecraftforge.event.ForgeEventFactory.doSpecialSpawn(net.minecraft.world.entity.Mob, net.minecraft.world.level.LevelAccessor, float, float, float, net.minecraft.world.level.BaseSpawner, net.minecraft.world.entity.MobSpawnType)'
at com.BrassAmber.ba_bt.block.tileentity.BTBaseSpawner.m_151311_(BTBaseSpawner.java:82) ~[BrassAmberBattleTowers-1.18.1-2.0.2.jar%2344!/:1.18.1-2.0.2]
at com.BrassAmber.ba_bt.block.tileentity.BTSpawnerBlockEntity.serverTick(BTSpawnerBlockEntity.java:56) ~[BrassAmberBattleTowers-1.18.1-2.0.2.jar%2344!/:1.18.1-2.0.2]
at net.minecraft.world.level.chunk.LevelChunk$BoundTickingBlockEntity.m_142224_(LevelChunk.java:673) ~[server-1.18.1-20211210.034407-srg.jar%2378!/:?]
at net.minecraft.world.level.chunk.LevelChunk$RebindableTickingBlockEntityWrapper.m_142224_(LevelChunk.java:768) ~[server-1.18.1-20211210.034407-srg.jar%2378!/:?]
at net.minecraft.world.level.Level.m_46463_(Level.java:476) ~[server-1.18.1-20211210.034407-srg.jar%2378!/:?]
at net.minecraft.server.level.ServerLevel.m_8793_(ServerLevel.java:324) ~[server-1.18.1-20211210.034407-srg.jar%2378!/:?]
at net.minecraft.server.MinecraftServer.m_5703_(MinecraftServer.java:868) ~[server-1.18.1-20211210.034407-srg.jar%2378!/:?]
... 5 more

Could you try updateing to the most recent forge version for 1.18.1? There was a fix they made for some spawner related stuff, (which this is) that might fix it.

that would be 39.1.2 -

thank you it worked ! Sorry I haven't tried this earlier.

No worries! Glad it worked :)

Hey there,
I am having the same issue, even though I followed your advice on updating forge.

Minecraft Version 1.18.1 & Forge 39.1.2
The version of the mod you are using: 1.18.1-2.0.2
If you are using any datapacks/self-created loot-tables etc: NO
Server or Singleplayer: MULTIPLAYER
OS: Windows 10

Any help would be much appreciated :)

Crash Log
Thread: Server thread
Stacktrace:
at com.BrassAmber.ba_bt.block.tileentity.BTBaseSpawner.m_151311_(BTBaseSpawner.java:82) ~[BrassAmberBattleTowers-1.18.1-2.0.2.jar%2342!/:1.18.1-2.0.2] {re:classloading}
at com.BrassAmber.ba_bt.block.tileentity.BTSpawnerBlockEntity.serverTick(BTSpawnerBlockEntity.java:56) ~[BrassAmberBattleTowers-1.18.1-2.0.2.jar%2342!/:1.18.1-2.0.2] {re:classloading}
at net.minecraft.world.level.chunk.LevelChunk$BoundTickingBlockEntity.m_142224_(LevelChunk.java:673) ~[server-1.18.1-20211210.034407-srg.jar%2363!/:?] {re:classloading}
at net.minecraft.world.level.chunk.LevelChunk$RebindableTickingBlockEntityWrapper.m_142224_(LevelChunk.java:768) ~[server-1.18.1-20211210.034407-srg.jar%2363!/:?] {re:classloading}
at net.minecraft.world.level.Level.m_46463_(Level.java:476) ~[server-1.18.1-20211210.034407-srg.jar%2363!/:?] {re:classloading,pl:accesstransformer:B}
at net.minecraft.server.level.ServerLevel.m_8793_(ServerLevel.java:324) ~[server-1.18.1-20211210.034407-srg.jar%2363!/:?] {re:classloading,pl:accesstransformer:B}
-- Block entity being ticked --
Details:
Name: ba_bt:bt_spawner // com.BrassAmber.ba_bt.block.tileentity.BTSpawnerBlockEntity
Block: Block{ba_bt:bt_land_spawner}
Block location: World: (-891,87,111), Section: (at 5,7,15 in -56,5,6; chunk contains blocks -896,-64,96 to -881,319,111), Region: (-2,0; contains chunks -64,0 to -33,31, blocks -1024,-64,0 to -513,319,511)
Block: Block{ba_bt:bt_land_spawner}
Block location: World: (-891,87,111), Section: (at 5,7,15 in -56,5,6; chunk contains blocks -896,-64,96 to -881,319,111), Region: (-2,0; contains chunks -64,0 to -33,31, blocks -1024,-64,0 to -513,319,511)
Stacktrace:
at net.minecraft.world.level.chunk.LevelChunk$BoundTickingBlockEntity.m_142224_(LevelChunk.java:673) ~[server-1.18.1-20211210.034407-srg.jar%2363!/:?] {re:classloading}
at net.minecraft.world.level.chunk.LevelChunk$RebindableTickingBlockEntityWrapper.m_142224_(LevelChunk.java:768) ~[server-1.18.1-20211210.034407-srg.jar%2363!/:?] {re:classloading}
at net.minecraft.world.level.Level.m_46463_(Level.java:476) ~[server-1.18.1-20211210.034407-srg.jar%2363!/:?] {re:classloading,pl:accesstransformer:B}
at net.minecraft.server.level.ServerLevel.m_8793_(ServerLevel.java:324) ~[server-1.18.1-20211210.034407-srg.jar%2363!/:?] {re:classloading,pl:accesstransformer:B}
at net.minecraft.server.MinecraftServer.m_5703_(MinecraftServer.java:868) ~[server-1.18.1-20211210.034407-srg.jar%2363!/:?] {re:mixin,pl:accesstransformer:B,re:classloading,pl:accesstransformer:B,pl:mixin:APP:balm.mixins.json:MinecraftServerAccessor,pl:mixin:APP:balm.mixins.json:MinecraftServerMixin,pl:mixin:A}
at net.minecraft.server.dedicated.DedicatedServer.m_5703_(DedicatedServer.java:328) ~[server-1.18.1-20211210.034407-srg.jar%2363!/:?] {re:classloading,pl:accesstransformer:B}
at net.minecraft.server.MinecraftServer.m_5705_(MinecraftServer.java:808) ~[server-1.18.1-20211210.034407-srg.jar%2363!/:?] {re:mixin,pl:accesstransformer:B,re:classloading,pl:accesstransformer:B,pl:mixin:APP:balm.mixins.json:MinecraftServerAccessor,pl:mixin:APP:balm.mixins.json:MinecraftServerMixin,pl:mixin:A}
at net.minecraft.server.MinecraftServer.m_130011_(MinecraftServer.java:668) ~[server-1.18.1-20211210.034407-srg.jar%2363!/:?] {re:mixin,pl:accesstransformer:B,re:classloading,pl:accesstransformer:B,pl:mixin:APP:balm.mixins.json:MinecraftServerAccessor,pl:mixin:APP:balm.mixins.json:MinecraftServerMixin,pl:mixin:A}
at net.minecraft.server.MinecraftServer.m_177918_(MinecraftServer.java:258) ~[server-1.18.1-20211210.034407-srg.jar%2363!/:?] {re:mixin,pl:accesstransformer:B,re:classloading,pl:accesstransformer:B,pl:mixin:APP:balm.mixins.json:MinecraftServerAccessor,pl:mixin:APP:balm.mixins.json:MinecraftServerMixin,pl:mixin:A}
at java.lang.Thread.run(Thread.java:833) [?:?] {}

Right on crashing it also mentioned something about Hexxit.jar not found, Forge.jar not found and TekkitLite.jar not found.
I cannot seem to find it in the log anymore though.

@RapidCamel

Hey! Appreciate you looking through the closed issues first and trying this fix!

2 questions:

What Minecraft launcher are you using?
And is this part of a modpack?

Hey JMilabmber,
thank you for your fast reply. I was not sure if that is the right way, commenting on a closed issue.
I checked the crashlog again and realized, I did not properly update forge.

reinstalled forge and now it works! Thank you again and sorry for the inconvenience.

Updating forge definitely solves this issue.

No worries! Glad that is the fix :).