Bug Report

On trying to rejoin my server on January 2, I had an error of missing registry entries. restarting the server, the following prompt was presented:

[04:16:11] [Server thread/INFO] [minecraft/DedicatedServer]: Preparing level "world"
[04:16:11] [Server thread/INFO] [FML]: Injecting existing registry data into this server instance
[04:16:12] [Server thread/INFO] [FML]: Registry VillagerProfession: Found a missing id from the world stevescarts:santa
[04:16:12] [Server thread/ERROR] [FML]: Unidentified mapping from registry minecraft:villagerprofessions
[04:16:12] [Server thread/ERROR] [FML]:     stevescarts:santa: 13
[04:16:12] [Server thread/WARN] [FML]: Forge Mod Loader detected missing registry entries.

There are 1 missing entries in this save.
If you continue the missing entries will get removed.
A world backup will be automatically created in your saves directory.

Missing minecraft:villagerprofessions:
    stevescarts:santa


Run the command /fml confirm or or /fml cancel to proceed.
Alternatively start the server with -Dfml.queryResult=confirm or -Dfml.queryResult=cancel to preselect the answer.
> /fml confirm
[04:19:50] [Server thread/INFO] [FML]: confirmed
[04:20:12] [Server thread/INFO] [FML]: World backup created at /mnt/minecraft/world-20200102-041950.zip.
[04:20:12] [Server thread/ERROR] [FML]: There are unidentified mappings in this world - we are going to attempt to process anyway

Expected Behaviour

I would expect the various christmas decorations to revert without issue, from Astral Sorcery, Steve's Carts, and Minecraft itself. Right now, players could not connect to the server that was running over christmas, and a restart with registry clean was required.

Possible Solution

Upgrade steve's carts to TechReborn/StevesCarts@4870dfd which disables all easter eggs.

Steps to Reproduce (for bugs)

Looking at the above commit, it checks for Constants.isChristmas = SCConfig.enableChristmas && isActive(Calendar.DECEMBER, 1, 31) || SCConfig.persistentChristmas;

1. Set server date to Dec 25 for maximum Christmas.
2. Force many different world elements to spawn by flying around. Make sure to find a villager santa.
3. Set server date to Jan 2.

It should present registry issues.

Logs

• Server Log: https://gist.github.com/Denubis/7c9efa70df1f17ae7cc1bfbd08bcaa82
• Client log: https://gist.github.com/Denubis/b7c74019b3afd058b0038b920aca21bf
• Crash Log:

[04:16:12] [Server thread/INFO] [FML]: Registry VillagerProfession: Found a missing id from the world stevescarts:santa
[04:16:12] [Server thread/ERROR] [FML]: Unidentified mapping from registry minecraft:villagerprofessions
[04:16:12] [Server thread/ERROR] [FML]:     stevescarts:santa: 13
[04:16:12] [Server thread/WARN] [FML]: Forge Mod Loader detected missing registry entries.

There are 1 missing entries in this save.
If you continue the missing entries will get removed.
A world backup will be automatically created in your saves directory.

Missing minecraft:villagerprofessions:
    stevescarts:santa


Run the command /fml confirm or or /fml cancel to proceed.
Alternatively start the server with -Dfml.queryResult=confirm or -Dfml.queryResult=cancel to preselect the answer.
[04:19:50] [Server thread/INFO] [FML]: confirmed```

## Client Information
<!--- Include as many relevant details about the environment you experienced the bug in -->
<!-- Please tell us how much memory you have allocated to the game. For Twitch/ATLauncher look in the settings -->
* Modpack Version:  3.1.2 hotfix
* Java Version: /usr/lib/jvm/java-8-oracle/jre/bin/java
* Launcher Used: MultiMC
* Memory Allocated: min 512M, max 16G
* Server/LAN/Single Player: Server
* Optifine Installed: No
* Shaders Enabled: Whatever default is

## World Information
<!-- Please provide the version of the modpack that the world was created in if known. Rough estimates are OK -->
* Modpack Version world created in: 3.1.2 hotfix
<!-- If there are any additional mods, please state them below -->
* Additional Content Installed: None

<!--- Additional Information if you are using a server setup (DELETE THIS SECTION IF YOUR ISSUE IS CLIENT ONLY) -->
## Server Information
* Java Version: ```openjdk version "1.8.0_232"
OpenJDK Runtime Environment (build 1.8.0_232-8u232-b09-0ubuntu1~16.04.1-b09)
OpenJDK 64-Bit Server VM (build 25.232-b09, mixed mode)

• Operating System: Ubuntu 16.04
• Hoster/Hosting Solution: openstack VM
• Sponge (Non-Vanilla Forge) Server:

Steve’s Carts seasonal events are disabled in this pack as it is. (SCConfig.enableChristmas == false - https://github.com/DarkPacks/SevTech-Ages/blob/master/src/config/stevescarts.cfg#L111). Even with the commit you highlight, the mod will still register “Santa” in the Christmas period and then stop registering it afterwards. It’s annoying, but it’s an issue with the mod and not one we can resolve at the pack level.

All you have to do is run /fml confirm on the server to resolve this though.

So I had the same problem, albeit on a different modpack (FTB Revelation 1.12.2). When I was attempting to run the command "/fml confirm" after the error, my server would jump to 100% RAM usage, then hang indefinitely. However, when I stopped the server and ran it with the argument "-Dfml.queryResult=confirm" to auto select /fml confirm, it got past the hanging and started up properly. This thread has been the only thing I could find over the last 3 days of constantly searching, so I wanted to put down the solution that worked for me.
My host is Nodecraft, if it matters.

So I had the same problem with FTB Revelation 1.12.2 and what worked for me was adding -Dfml.queryResult=confirm to the start file.

@rtm516 I get the same issue, sadly.

I've reposted this on the Steve's Carts github, since it seems to be an issue with their mod specifically:
TechReborn/StevesCarts#198

@rtm516 Can you try restarting your server a second time? After adding that flag my server booted and I got the same issue you did. I had to cold-restart a second time for it to load correctly. I also used a fresh install of revelations client-side each time, if that helps.

So I had the same problem, albeit on a different modpack (FTB Revelation 1.12.2). When I was attempting to run the command "/fml confirm" after the error, my server would jump to 100% RAM usage, then hang indefinitely. However, when I stopped the server and ran it with the argument "-Dfml.queryResult=confirm" to auto select /fml confirm, it got past the hanging and started up properly. This thread has been the only thing I could find over the last 3 days of constantly searching, so I wanted to put down the solution that worked for me.
My host is Nodecraft, if it matters.

This is still an issue in 2021. I'm getting the same problem with the latest version of that mod pack, except it just loops back to the same confirmation dialog for me if I confirm it. It started happening after Christmas on its own.

This also gives users this error if connecting on a client started after the end of December if the server started before that.

This also gives users this error if connecting on a client started after the end of December if the server started before that.

I had the same error as you did, I've managed to login back to my server after some config changes. Not sure if this would work for you but I went into the FTB Revelations directory and disabled events from Steve's Carts. The config should be in FTB Revelation\config\stevescarts.cfg

Scroll down and under events
disable these lines:

B:"Enable Christmas"=false

Restart MC and try again.

All Steve's Carts seasonal events are disabled in this pack. Locking as FTB Revelations is off topic.