Context

Hi, I ran into an issue with steam rails for create 6 for 1.20.1

Initially, I put it in a big modpack, so afterwards I tried to isolate the mod causing the issue.

It looks like several mods can affect the loading, so I don't know if it's relevant to list them (and I did not try to launch the game with only them and create + steam rails, as it could take a long time)

The issue seems to be related to this line :

NullPointerException: Registry entry not present: create:copycat

Thanks for the mod and for your time

Crash Report

NullPointerException: Registry entry not present: create:copycat

Atm I can't provide one, feel free to ask for one if needed.

I'm also getting this error nearly every time I start both my server and client.

I got it several times, removed some mods, it went away, updated SnR, issue came back.

Annoying.

EDIT: And the next run loaded normally...

same issues with my server pack(gonna have to remove it from my pack until it works on servers)

As the original submitter hasn't posted a crash report yet, I'll post the one I've been getting on my server: https://mclo.gs/BiUuDAk

In case a slightly different crash with the same outcome would help: https://mclo.gs/b5pzIU0

Issue #633 seems to provide the most information on this crash. I can confirm my server is also running the latest versions of SnR and TFMG.

I don't have TFMG but I have the issue. I'm not sure wich mod causes the issue to happen, but one thing I did :
I put the 1st half of my modpack with create + snr, it loaded.
I put all of my modpack with create + snr, it crashed.
I put only the 2nd half of my modpack with create + snr, it loaded.

It's like the issue will happen only with a combo of mods, really strange and really annoying because it's hard to find the issue.
I hope there is a way to find a fix.

My server crash was also without TFMG, though it has a bunch of other mods that might be conflicting.
I can also confirm that removing and adding mods seems to make the issue appear and disappear seemingly randomly.

It's like the issue will happen only with a combo of mods, really strange and really annoying because it's hard to find the issue.
Could you provide your crash and latest.logs from your full modpack?

Could you provide your crash and latest.logs from your full modpack?

Sure, here :

latest.log
debug.log

crash-2025-06-27_08.22.26-client.txt

Full logs from dedicated server crash with around 120 mods.
Latest.log
Debug.log

The crash occurs for me when I have 'Rechiseled: Create 1.0.2a' installed. After removing the mod, Minecraft starts with SnR without crashing.

The crash occurs for me when I have 'Rechiseled: Create 1.0.2a' installed. After removing the mod, Minecraft starts with SnR without crashing.

Removing rechiseled create didnt work for me ;(

This issue seems to be very complicated, as there's not too much overlap between the mods used in each of these crashes, and the logs don't provide much information it seems.

This may be an issue with Copycats+, I'll notify of this issue on their end as well.

Full logs from dedicated server crash with around 120 mods. Latest.log Debug.log

Registry entries not being present are usually caused by an error in the startup earlier on. In this case its likely this https://mclo.gs/be6MRfC#L46

This may be an issue with Copycats+, I'll notify of this issue on their end as well.

Unfortunately I got a crash without Copycats+
https://mclo.gs/vaokeOd

In my case, no crash with Copycat+

In that case, we're back to this issue having no suspected mods at the root of it. I attempted to get help from the Modded Minecraft discord server, but I had no luck there.

Whats really weird is one of my friends gets this crash while my game launches perfectly fine. We have identical modpacks and forge versions, I even made sure java versions were the same and had him reinstall the entire pack through an installer so its the exact same files that I have but he still crashes. Not sure if this helps or hurts finding the root cause of this issue its really strange.

Whats really weird is one of my friends gets this crash while my game launches perfectly fine. We have identical modpacks and forge versions, I even made sure java versions were the same and had him reinstall the entire pack through an installer so its the exact same files that I have but he still crashes. Not sure if this helps or hurts finding the root cause of this issue its really strange.

A similar thing happens to me, as it crashes on the server-side, but on the client-side, it launches perfectly fine.

Crash log: https://mclo.gs/WI41ErI

https://mclo.gs/Y7a6jXZ

have the exact same issue with a modpack on a server I am in

Whats really weird is one of my friends gets this crash while my game launches perfectly fine. We have identical modpacks and forge versions, I even made sure java versions were the same and had him reinstall the entire pack through an installer so its the exact same files that I have but he still crashes. Not sure if this helps or hurts finding the root cause of this issue its really strange.

A similar thing happens to me, as it crashes on the server-side, but on the client-side, it launches perfectly fine.

It started happening on my server too and I was just able to fix it by deleting the libraries folder and generating a new one. I'm assuming you can do something similar for a client problem.

Posting my log: https://mclo.gs/Hsxe0Hg
i think it's time for some binary search

It started happening on my server too and I was just able to fix it by deleting the libraries folder and generating a new one. I'm assuming you can do something similar for a client problem.

Wow ! The game launched by removing libraries, but on the main menu I got a toast "reload resources failed".
And the animated menu of ice and fire or aether looks like this atm :

But then, I tried creating a world and got this crash :

crash-2025-07-01_07.45.31-client.txt

Anche io ho lo stesso problema non sarebbe giusto che lo sviluppatore venga a conoscenza di questo problema?

Confermo che il problema nel mio caso è solo lato server perché il client si avvia correttamente

Figured I would just go ahead and add my own crash log in case it helps https://mclo.gs/HIjflE5 but I had a weird thing with my crash.
The first time i installed my servers pack it worked fine on first launch but when I closed and increased my allocated ram it wouldn't launch again after that. (yes I tried turning it back down and it still didn't launch again)
assuming I just got lucky because of first launch being weird, idk tho

#654 (comment) Someone found a temp "fix" for my issue, assuming issue 611 is the same thing so try this if you really want to play

I'm having this issue as well with a very large modpack. It works on client, but when loading the server pack I get this crash:

java.lang.NullPointerException: Registry entry not present: create:copycat

https://mclo.gs/bsMm4mO

Are devs have any idea how to fix it? Seems to be a lot of people have this issues

I haven't yet found anything in anyone's logs indicating the root cause. If someone is able to binary search their modpack and can find the minimal set of mods needed to replicate this crash, that would be extremely helpful.

Alright, I've got an update for y'all.

There was a very useful log in #629, which has revealed the problem.

In 6.0.?, Create made its Create.REGISTRATE field private, and provided an alternate API for mods to create registration callbacks. Unfortunately, this API is completely non-functional, for the reasons mentioned below.

The API in question is CreateRegistrateRegistrationCallback.register

1. if you call the API after Create loads, it will not register the callback (doesn't show up in logs that I can tell, but still bad)
2. if you call the API while Create is loading, it will throw a ConcurrentModificationException (see https://mclo.gs/hAk2CsU)
3. even if you manage to register the callback, it will explode when called, since the callback handler tries to get the registered object immediately when a RegistryEntry is added, even though the object won't be registered (into Minecraft registries) for a long time yet (this is the culprit responsible for the most common crash, Registry entry not present: create:copycat)

The code responsible for (3) is at https://github.com/Creators-of-Create/Create/blob/e0c859a9277510af67621e95ead5b42d86c243b1/src/main/java/com/simibubi/create/foundation/data/CreateRegistrate.java#L130

Ultimately, I think the solution here is to create an inner class in CreateRegistrate that exposes the various methods that are safe for other mods to call (notably, addRegisterCallback)

cc: @IThundxr
I'll open a proper issue on the Create repo tomorrow, just wanted to write this all down here before I forgot.

Alright, I've got an update for y'all.

There was a very useful log in #629, which has revealed the problem.

In 6.0.?, Create made its Create.REGISTRATE field private, and provided an alternate API for mods to create registration callbacks. Unfortunately, this API is completely non-functional, for the reasons mentioned below.

The API in question is CreateRegistrateRegistrationCallback.register

1. if you call the API after Create loads, it will not register the callback (doesn't show up in logs that I can tell, but still bad)
2. if you call the API while Create is loading, it will throw a ConcurrentModificationException (see https://mclo.gs/hAk2CsU)
3. even if you manage to register the callback, it will explode when called, since the callback handler tries to get the registered object immediately when a RegistryEntry is added, even though the object won't be registered (into Minecraft registries) for a long time yet (this is the culprit responsible for the most common crash, Registry entry not present: create:copycat)

The code responsible for (3) is at https://github.com/Creators-of-Create/Create/blob/e0c859a9277510af67621e95ead5b42d86c243b1/src/main/java/com/simibubi/create/foundation/data/CreateRegistrate.java#L130

Ultimately, I think the solution here is to create an inner class in CreateRegistrate that exposes the various methods that are safe for other mods to call (notably, addRegisterCallback)

cc: @IThundxr I'll open a proper issue on the Create repo tomorrow, just wanted to write this all down here before I forgot.

Then how come some people can play it without any issues?
From my interpretation create developers made a really bad API, but it has to sometimes work?

Fixed in ba14e5a

The proper API should be usable after Creators-of-Create/Create#8890 is merged