java.lang.IllegalStateException: Failed to load description for particle immersiveengineering:fluid_splash
at net.minecraft.client.particle.ParticleManager.func_215236_a(ParticleManager.java:226) ~[?:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A}
at net.minecraft.client.particle.ParticleManager.lambda$null$0(ParticleManager.java:169) ~[?:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A}
at net.minecraft.client.particle.ParticleManager$$Lambda$4150/735754293.run(Unknown Source) ~[?:?] {}
at java.util.concurrent.CompletableFuture$AsyncRun.run(CompletableFuture.java:1618) ~[?:1.8.0_51] {}
at java.util.concurrent.CompletableFuture$AsyncRun.exec(CompletableFuture.java:1610) ~[?:1.8.0_51] {}
at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289) ~[?:1.8.0_51] {}
at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1056) ~[?:1.8.0_51] {}
at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1689) ~[?:1.8.0_51] {}
at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:157) ~[?:1.8.0_51] {}
Caused by: java.io.FileNotFoundException: immersiveengineering:particles/fluid_splash.json
at net.minecraft.resources.SimpleReloadableResourceManager.func_199002_a(SimpleReloadableResourceManager.java:63) ~[?:?] {re:classloading,pl:accesstransformer:B}
at net.minecraft.client.particle.ParticleManager.func_215236_a(ParticleManager.java:205) ~[?:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A}
... 8 more

Downgrade Forge to 34.1.25.

This will be addressed in future releases.