Ugdhar

Post your entire debug.log to a paste site, and then post the link here; it should have information that will help find what the issue is.

https://docs.minecraftforge.net/en/1.20.x/concepts/sides/

Looks like you may have some fabric mods in there, those won't work with forge. Start by removing any mod that has the word "fabric" in the filename.

This one jumped right out at us: I think this one might mean you need to update your Java to a more recent Java 8:

I feel as though looking at the code for the nametag would give you something to work with, isn't that used on entities to give them names? Honestly never used one before lol, but if it were me, that's where I would start.

Check thread dates, this guy has prob given up/moved on since this post is nearly 2 years old

If you remove valkyrienskies does it work?

That's a Fabric log, this is the Forge forums.

When you make a change, if it is still not working, post new logs for further help.

There are examples of capabilities on the forums and in the forge docs as well as the forge github that you could use to get started. Poke around some. You can use this to get started: https://docs.minecraftforge.net/en/latest/datastorage/capabilities/ Try some stuff, write some code and share a link to it, it's like bait when fishing, you'll get a bite faster/more bites than an empty hook!

If it were me, I'd probably take a look into capabilities, and add whatever the item handler capability is called (been a hot minute since I've tinkered with them, so no idea if they've changed) to the mobs I wanted when they are spawned into the world. Give it a try, if you run into problems, post your code (pref to a working github repository) for further help. Good luck!

The way this reads, you're asking how to stop and start the server. Just type stop and press enter at the server console, and it will stop the server. Then run whatever command executes the server (often times a batch file, ending with .bat) to start it back up. If that's not what you mean, then I don't think you can "refresh" the server without wiping stuff out, and more or less starting the world over.

You should make your own thread with your issue, instead of posting on someone else's old post. But it looks like you are missing mods that mods you have require.

Looks like you are missing some mods that other mods require.

That does not look like a complete debug.log. You should post it to a paste site like hastebin or something, and then post the link to it here. However, I would remove optifine and see if that helps.

Have you made an item? That's the first step, an item that does nothing that you can hold in your (off)hand. After that, I guess it somewhat depends what passive effect you are looking for. Will this need to be applied on equip/removal? Or is it something that can be detected elsewhere (i.e. damage-taking event, checking for totem equipped, then reducing dmg)

Are you using the curseforge launcher? If so, you will need to go into the settings and enable the debug.log. I do not use the curseforge launcher, so cannot tell you the exact steps for how to do so.

Those logs do not look complete, they look as though they've been cut off. That second log doesn't even have a crash in it. When you have a lot of things and need to find the one(s) that are problematic, there's a method for doing it that's easier than 1 by 1: Remove half of the existing things, and put them aside. Run the program / game. Does the issue still exist? If YES: Repeat from step 1 with the current things. IF NO: Swap out the current things with the ones set aside, and repeat from step 1. Repeat this process until the problematic thing/s have been found.

Apologies, not sure how I thought it was still there, that line was from the old log, sorry. Broken or conflicting mixin(s). Honestly I can't tell which mod(s) exactly are doing it, so unless someone else knows, you'll have to trial and error remove mods and test to figure out which ones aren't working together. The joys of mod developers directly modfiying the minecraft code, weeee

That is either not the debug.log, or it is not complete. There is no crash present in that log you posted.

Search github for projects, many of them are open source and published for anyone to look at. There may be ways to reverse-engineer someone's code if they do not make the source available, but it's usually best to have permission/find open-source mods to look at.

Make sure you have the latest amd gpu drivers

This crash still uses optifine.

I'm not seeing that error in that log, it should tell you the mod using the improper character in the resourcelocation right around that error. Remove/update that mod,

Remove Optifine and try again, if it crashes again post a new log please. Also, logs are easier to read if you paste them to a paste site like hastebin or a github gist.