Please help, i cannot understand code... help me find the mods that are making me suffer

---- Minecraft Crash Report ----// Hi. I'm Connector, and I'm a crashaholic - Pastebin.com

Hmmmmm... It looks like your problem might be being cause by a transformer function that has previously failed. Basically, the game uses transformers to literally rewrite Minecraft's code. Think of these functions like a courier service. Let's say you buy a package from FedEX. They put your package in their big ol' trucks and send 'em off. However, let's say that this truck suddenly gets stopped to be searched, e.g. the transformer editing the package (the code). The guy searching the truck finds your package and he goes, "Hey, man, this package is a bit strange so we gotta' change it a bit, here-" and he opens up the package, removes a few things, adds a few things, and finally puts the package back in the truck and sends it off. When you get your package (again, the code), it will be changed by the man who searched the truck (again, the transformer). Everything went alright, HOORAY! Now, let's say this man searching your truck runs into a bit of an issue while modifying your package, and he... gets struck by and asteroid or something, idk. Because he failed so catastrophically, you will NEVER get your package, so the truck will just have to drive off without your package. Now let's say we have another guy on the track this time that wants to search the truck, and let's say he's looking for that same package that the first guy messed up with. He goes into the truck, looks around a bit, and says, "wth, there ain't nothin' here man." Then he calls the police and says something like, "ClassMetadataNotFoundException." This could be what has happened here, although I'm not too positive. But basically, the entire package (the code needed to be modified) is GONE! But here's the thing, the exception shown in your crash report is NOT going to be the one that's actually of note, because the original guy didn't throw an exception. What you need is evidence of what failed to change the class beforehand. Here's what you can do. In your log file, try finding the point where the exception is initially thrown, then try scrolling up and see what's there. If you see anything of note, please report it here. If all else fails and nobody is able to help you here, then as a last resort you could post the log file, although I wouldn't exactly recommend this right off the bat, who knows what might be in there.

Hope this helps ya' out man!

Not sure if the wall of text is helpful. It looks like a Mixin from Iris is failing. Try loading without that and see if that helps.

Thank you both so much! I'll try it tomorrow since it's quite late.

Alr, I just looked at the individual mods here (MixinBooter and Iris Flywheel Compat). I'm going to try my best to add some input here for when you get back next morning WITHOUT making a huge text wall again. Before your exception is thrown here and your game crashes, in your log you should see something like this: "Error loading class:". Try a CONTROL+F search to find it in your log file. If you do not see this message, then I really hope you have a bible on hand and a good prayer in mind, because you might be screwed. Hopefully that's not the case though. If you find this message in your log file, please post it here. Also, could you provide the name of the modpack you are using?

One more thing I should add. I'm not exactly sure that removing Iris Flywheel Compat would work, but I would encourage you to do so anyways just in case it does work. If it does not work, then the problem is 100% being caused by a bad transformer function, in which case you should provide a link to your modpack. ONE MORE THING: if you are using any other additional mods in your modpack, please provide them here, even if they are hacked clients; I cannot help you with anything revolving around hacked clients, but knowing if you have a hacked client mod will still help determine the source of the problem. Hopefully removing Iris-Compat works...