Minecraft Failed to synchronize registry data from server Reddit

I've been hosting an "open lan" server with my son, who until recently, connected to it fine. We're using a custom modpack that I assembled on Curseforge. He's been getting the registry synchronization error on his comp. I searched google for this error flag and confirmed that it meant that MC, Forge, the mods and config all have to be the same version. So I exported the current version of the modpack that's on the "open lan" server, from within the CF client, selecting all of the check boxes except shaders and screenshots. I then imported it with my son's CF client. He still get the error, but I noticed that it's only when connecting to our existing world. I made a test world and he connected fine. I think that it's likely that importing the pack to his CF client did nothing, but I didn't test the new world prior to confirm. It just seems like a messed up world (that only I can load).

I suspect that it's from my testing 2 mods (Resourceful Bees and Artifacts) and promptly removing them because they crashed my client (lan host) after loading the world. It happened twice after I opened Journey Maps to place a beacon in a newly explored area. I'm not sure if that was coincidental because both times it was so soon after the world loaded. I didn't run them on my son's instance. He wanted to play and I didn't have time to troubleshoot that issue. I can't wait until he's old enough to help me with this stuff or at least understand it's complexity lol.

Is there anything that I can copy from my instance folder that will put our world files (for lack of better way to describe them) back in parity? Or can I somehow keep our progress, otherwise? I can't seem to find the same exact scenario in my searches, or if I have, they went unresolved. I've heard about World Edit, but not entirely sure how I would apply it to this problem.

Many thanks!

hello all, i am trying to run a LAN Minecraft server off my PC. i had a friend bring his PC over to my house, we got our mod packs EXACTLY the same (we even tried updating all mods and forge) and he get the error message in title. he was bale to join before this which is weird. we cant start over as we have been working on this world for almost a year And its a custom map, any help is greatly appreciated.

never really had to post but ive tried absolutely everything, curse forge is having issues so i decided to manually install it to play on my friends server (All the mods 7). spent 6 hours trying fix it and other issues, to no avail please help :( thank you.

the log error is:

[13Sept2022 00:20:36.387] [Render thread/ERROR] [net.minecraftforge.network.HandshakeHandler/FMLHANDSHAKE]: Missing registry data for impl connection:

minecraft:item: mysticalagriculture:allthemodium_essence

minecraft:item: mysticalagriculture:allthemodium_seeds

minecraft:item: mysticalagriculture:azure_silver_essence

minecraft:item: mysticalagriculture:azure_silver_seeds

minecraft:item: mysticalagriculture:crimson_iron_essence

minecraft:item: mysticalagriculture:crimson_iron_seeds

minecraft:item: mysticalagriculture:unobtainium_essence

minecraft:item: mysticalagriculture:unobtainium_seeds

minecraft:item: mysticalagriculture:vibranium_essence

minecraft:item: mysticalagriculture:vibranium_seeds

minecraft:block: mysticalagriculture:allthemodium_crop

minecraft:block: mysticalagriculture:azure_silver_crop

minecraft:block: mysticalagriculture:crimson_iron_crop

minecraft:block: mysticalagriculture:unobtainium_crop

minecraft:block: mysticalagriculture:vibranium_crop

[13Sep2022 00:20:36.387] [Netty Client IO #2/ERROR] [net.minecraftforge.network.HandshakeHandler/FMLHANDSHAKE]: Failed to load registry, closing connection.

[13Sep2022 00:20:36.397] [Netty Client IO #2/ERROR] [net.minecraftforge.network.HandshakeHandler/FMLHANDSHAKE]: Connection closed, not continuing handshake

Copying a pasting this from another subreddit I posted in.

So in my discord, I set up a Minecraft server for something extra for the community to take part it. I have mods installed (not a modpack), and so far I've gotten 2 people to join successfully after some troubleshooting.

So I can join and others can join as long as the installation is followed properly. There's an issue with one of the people in my server, where she can not join a multiplayer server on java. I've been told in the past, she's tried joining friends servers, and consistently she's gotten that same exact error, regardless of mods being installed on the server or not. It seems that she cannot join any Java multiplayer server, but can join realms just fine.

I helped get her set up on installing the mods, right forge version, everything. We followed it to a T, yet still the issue persists. So I know this is not mod related, and since there's no guides I've found that detail this error in this specific situation, I wanted to post here to get some input from some more experienced Minecraft gamers.

Thoughts, folks? Anything is appreciated, and I'll answer as many questions as I can. Thanks in advanced.