That doesn't look like a Forge 1.17.1 log to me... you're sure that's the correct log?

Please provide debug.log (more info on where this file can be found, and how to provide it, can be found in my signature below)

Packs are not typically upgradable across minecraft versions, so if you're using a pack in an out-of-support version you're a bit screwed.

Have you read the previous responses or are you just jumping on the bandwagon and hoping wee can do something about it?

Please refer to Optifine's changelog for compatibility information

1.12 is no longer supported on this forum.

Please update to a modern version of Minecraft to receive support.

Ok that is the correct place (I had to ask because some people think the profile list is the version list).
Do you have antivirus software installed?

        Mod File: genericeco-1.16.5-1.3.jar
        Failure message: Generic Ecosphere has class loading errors
                java.lang.RuntimeException: Attempted to load class net/minecraft/client/renderer/entity/EntityRenderer for invalid dist DEDICATED_SERVER
        Mod Version: 1.16.5-1.3
        Mod Issue URL: NOT PROVIDED
        Exception message: java.lang.RuntimeException: Attempted to load class net/minecraft/client/renderer/entity/EntityRenderer for invalid dist DEDICATED_SERVER

Behold another busted client-only mod

Please consider learning Java and making your mod properly.

Freezes aren't crashes and can be caused by a great many things.
Crashes are easier to fix as you can determine where things went wrong much easier.

Can you provide screenshots of where you're looking? Just to be sure

I would suggest asking in a space more focused on the mod, especially given that it's stuck on versions we dropped support for ages ago.

Biomes You'll Go is the prime suspect

1.12 is no longer supported on this forum.

Please update to a modern version of Minecraft to receive support.

Did you update Java today? Java 17 dropped and it had an issue that was only just fixed in 37.0.60

1.12 is no longer supported on this forum.

Please update to a modern version of Minecraft to receive support.

Java 17 literally released today and apparently removed some stuff used by a library we use... so no, not compatible

There's so much going wrong in these logs it's hard to tell which, if any, of them are causing the freeze issue...
KubeJS and Ice and Fire seem to be the big ones

Are you sure this is the whole log?

1.12 is no longer supported on this forum.

Please update to a modern version of Minecraft to receive support.

Please provide debug.log (more info on where to find it and how to provide it can be found in my signature below)

Please use one of the pastes sites in my signature below for providing logs, Google Docs is meant for documents, not raw text files and the extra formatting makes logs unreadable

I have never, ever seen the game crash without putting any info anywhere...

Have you tried any other Forge versions?

Were you changing resource packs or data packs when this crash occurred?

Misleading thread title, be careful