Error in multiplayer when using mod

Started by Dreadplot329910 on

Topic category: Help with Minecraft modding (Java Edition)

Joined May 2025
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Error in multiplayer when using mod

Recently, whenever I try to play multiplayer with my mod, errors occur. When hosting with the essential mod, the player joining is instantly disconnected. I also tested it with e4mc mod but the player just got the text, 

"The server send registries with unknown keys: ResourceKey[neoforge:fluid_ingredient_type / neoforge:compound],

ResourceKey[neoforge:fluid_ingredient_type / neoforge:components],,

ResourceKey[neoforge:fluid_ingredient_type / neoforge:difference],

ResourceKey[neoforge:fluid_ingredient_type / neoforge:tag],

ResourceKey[neoforge:fluid_ingredient_type / neoforge:empty],

ResourceKey[neoforge:fluid_ingredient_type / neoforge:intersection],

ResourceKey[neoforge:fluid_ingredient_type / neoforge:single]"

 

When I test with the MCreator Testing Server, it just says Connection refused: getsockopt.

When in singleplayer everything works fine. It's just as soon as another player tries to join the/a server.

Joined Feb 2024
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This is the review of …
Wed, 07/09/2025 - 19:20

This is the review of ​Gemini:

 

It sounds like you're encountering a specific error related to NeoForge fluid ingredients when trying to play multiplayer with MCreator. This type of error often points to a mismatch or issue with how fluids are being handled or defined in your mod, particularly when trying to synchronize data between client and server in a multiplayer environment.

Here's a breakdown of what those "ResourceKey" messages likely mean and some common solutions:

What the Error Messages Mean:

The ResourceKey[neoforge:fluid_ingredient_type / ...] messages indicate that NeoForge (the modding API MCreator uses for modern Minecraft versions) is having trouble identifying or processing different types of fluid ingredients. These "types" are used to define how fluids are handled in crafting recipes, world generation, or other modded features.

  • neoforge:compound: Suggests an issue with a complex fluid ingredient made up of multiple parts.
  • neoforge:components: Similar to compound, refers to the individual parts of a fluid ingredient.
  • neoforge:difference: Implies an operation where one fluid ingredient is subtracted from another.
  • neoforge:tag: Problems resolving a fluid based on a Minecraft tag (a way to group similar items/fluids).
  • neoforge:empty: Could indicate an attempt to use an undefined or empty fluid ingredient.
  • neoforge:intersection: Issues with finding common elements between two fluid ingredients.
  • neoforge:single: Problems with a simple, single fluid ingredient.

Common Causes and Solutions:

  1. Mod Incompatibility/Version Mismatch:
    • Cause: The most common culprit. If you or your friends are using different versions of your mod, MCreator itself, NeoForge, or other installed mods, these types of desynchronizations can occur.
    • Solution:
      • Ensure everyone has the EXACT same mod file. Send the compiled .jar file of your MCreator workspace to everyone playing.
      • Verify NeoForge versions. When you export your mod from MCreator, it's built for a specific NeoForge version. Make sure everyone has that precise version of NeoForge installed in their Minecraft instance.
      • Check other mods. If you have other mods installed, try removing them one by one to see if one of them is causing a conflict with your MCreator mod's fluid handling.
  2. Corrupted Workspace/Export:
    • Cause: Sometimes the MCreator workspace can get a bit corrupted, or the export process might not complete correctly.
    • Solution:
      • Clean and Rebuild: In MCreator, try going to "Workspace" -> "Clean build folder" and then "Workspace" -> "Recompile and regenerate code." After that, export your mod again.
      • Test in Singleplayer: Does your mod work perfectly in singleplayer? If it does, the issue is almost certainly related to multiplayer synchronization.
  3. Fluid Definition Issues in Your Mod:
    • Cause: You might have inadvertently created a fluid in MCreator that has an improper or incomplete definition, especially in how it interacts with recipes or other game mechanics.
    • Solution:
      • Review your custom fluids: Go through all the custom fluids you've created in MCreator.
      • Check recipes involving fluids: If you have custom crafting recipes, smelting recipes, or other processes that use or produce your custom fluids, double-check their definitions for any inconsistencies.
      • Consider simple fluids first: If you're new to fluids, try starting with very basic fluid definitions and gradually add complexity.
  4. Network/Server-Side Issues (Less Common for this specific error):
    • Cause: While less likely to cause this specific error, general network problems or server configuration issues can sometimes manifest in strange ways.
    • Solution:
      • Restart the server/client: A simple restart can often clear up temporary glitches.
      • Check server logs: If you're running a dedicated server, look at the server console/logs for any other error messages that might give more context.

How to Provide More Information (If the above doesn't help):

If you're still stuck, providing more details will help narrow down the problem:

  • MCreator version: (e.g., 2024.1, 2023.4)
  • Minecraft version: (e.g., 1.20.1, 1.20.4)
  • NeoForge version: The exact version your mod is built for.
  • Mod details: What kind of custom fluids do you have? Are they used in any specific recipes or world generation features?
  • Full crash report/logs: If you get a full crash report (usually in your .minecraft/crash-reports folder or server logs), that's invaluable. Look for lines that mention your mod or the neoforge:fluid_ingredient_type error.

By systematically going through these troubleshooting steps, you should be able to identify and resolve the multiplayer fluid ingredient issue in your MCreator mod.