Mod Version:
DynamicSurroundings-1.12.2-3.4.7.2

Forge Version:
1.12.2-forge1.12.2-14.23.1.2587

Link to crash log (if applicable):
[main/ERROR] [FML]: Unable to determine registrant mod for org.blockartistry.DynSurround.client.sound.SoundManagerReplacement@4bf5b473. This is a critical error and should be impossible
java.lang.Throwable: null
at net.minecraftforge.fml.common.eventhandler.EventBus.register(EventBus.java:74) [EventBus.class:?]
at org.blockartistry.DynSurround.client.sound.SoundManagerReplacement.(SoundManagerReplacement.java:124) [SoundManagerReplacement.class:?]
at net.minecraft.client.audio.SoundHandler.(SoundHandler.java:63) [cho.class:?]
at net.minecraft.client.Minecraft.func_71384_a(Minecraft.java:472) [bib.class:?]
at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:377) [bib.class:?]
at net.minecraft.client.main.Main.main(SourceFile:123) [Main.class:?]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_151]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_151]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_151]
at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_151]
at net.minecraft.launchwrapper.Launch.launch(Launch.java:135) [launchwrapper-1.12.jar:?]
at net.minecraft.launchwrapper.Launch.main(Launch.java:28) [launchwrapper-1.12.jar:?]

Description:
Just the above error in the startup log.

Oh, and double check you are using the correct version of DS with the correct version of MC. Reason I say this is because I just dropped the 1.11.2 version of DS into a MC 1.12.2 instance and got that error.

This is a strange one. Can you try Forge version 14.23.1.2581? It's what I am currently using and do not see an issue.

I have been planning on changing how my static event handlers were registered. Because you encountered this particular issue I bumped up my priority on that work. Not sure if it will fix this issue you are seeing, but there is a good chance it will.

Well... that was weird... I have tried to reproduce it and it doesn't happen any more - not only that I've check the log files and there is no trace of it in their either... when I originally found it I culled it from the Official Minecraft Launcher's Game Output window which shows a random selection of information (not just FML or just MC)... so I'm now mystified where that came from because it was doing it consistently at the time!

My sincere apologies for wasting your time :(

P.S. I tried Forge 2555 (as it was to hand) as well as 2587 and the version of DS was about an hour old from Curse when I downloaded it... so I presume it was the correct version on their site - I've not changed it since though so I don't know what happened to the error! Is it maybe caused by another mod overlapping initialisation with DS and not necessarily always doing it in the same order? (I'll keep an eye out for it in future and get back to you if I can pin something down (assuming it ever happens again). Again, apologies :(

No worries. I would rather hear these things than not. :)

Pushed v3.4.8.3 to CurseForge. It has changes related to registration of static event handlers that may improve the situation, if it ever occurs again. :)