Encounter the rei not fully initialized error and restore full functionality without panic. Follow this guide carefully, apply each step methodically, and resolve the issue efficiently. This article is written in imperative form, meaning every section tells you exactly what to do.
Understand What “REI Not Fully Initialized” Means
Start by recognizing the meaning of the rei not fully initialized message. Treat it as a mod loading failure, not a fatal game error. Accept that Roughly Enough Items (REI) has started loading but failed to complete its initialization process.
Acknowledge that REI relies on:
- External APIs
- Recipe synchronization
- Plugin hooks from other mods
If any of these fail, REI stops midway and displays this message. Do not ignore it, because recipes, item lists, and mod integrations will not appear correctly.
Identify the Most Common Causes Immediately
Diagnose the problem before applying fixes. Assume one or more of the following causes exist:
- Missing dependencies like Architectury API or Cloth Config
- Version mismatch between Minecraft, REI, and other mods
- Mod conflicts caused by overlapping recipe viewers
- Server synchronization delays in multiplayer
- Corrupted mod files or incomplete downloads
Understand this clearly: REI does not fail randomly. Something blocks its final loading stage.
Update REI and All Required Dependencies
Begin with the most effective solution. Update everything.
- Delete the existing REI mod file
- Download the latest compatible version for your Minecraft version
- Install or update these mandatory dependencies:
- Architectury API
- Cloth Config
- Fabric API (Fabric only)
Never mix Forge and Fabric versions. Confirm your mod loader before downloading
Restart the game after updating. Do not skip this step.
Reload REI Plugins Inside the Game
Force REI to complete initialization manually.
- Launch Minecraft
- Enter a world
- Open the REI interface
- Click the Settings (⚙️ icon)
- Select Reload Plugins or Reload All
Wait patiently while REI refreshes its data. This action often completes unfinished initialization tasks and immediately restores recipes.
Use this step especially if REI loads partially but appears empty.
Check for Mod Conflicts and Remove Duplicates
Eliminate conflicts aggressively.
- Remove JEI, EMI, or other recipe viewer mods
- Disable recently added mods one by one
- Test the game after each removal
Remember: Only one recipe viewer should run at a time. Multiple viewers compete for the same data and cause initialization failures.
If the error disappears after removing a mod, you have identified the conflict.
Test Single Player Before Multiplayer
Force REI to initialize locally.
- Launch Minecraft
- Create or open a single-player world
- Wait for full world loading
- Open REI and confirm recipes appear
- Exit the game
- Rejoin your multiplayer server
This method allows REI to build its recipe cache locally, which often fixes server-side loading issues.
Apply this step especially when rei not fully initialized appears only on servers.
Reinstall the Modpack Cleanly
Perform a clean installation if basic fixes fail.
- Back up your worlds
- Delete the entire modpack folder
- Reinstall the modpack from a trusted launcher
- Launch once without adding extra mods
- Confirm REI loads correctly
Avoid manually copying old config files. Let the modpack generate fresh ones.
This step resolves corrupted downloads, a common hidden cause of initialization errors.
Inspect Game Logs for Hidden Errors
Locate and read the logs.
- Navigate to:
.minecraft/logs/latest.log - Search for:
REIArchitecturyplugin failedmissing stage
Use the log to identify exact mods blocking initialization. Remove or update them accordingly.
Treat logs as diagnostic tools, not optional reading.
Apply Advanced Fixes if the Error Persists
Take advanced action only if necessary.
- Increase allocated RAM
- Disable performance mods temporarily
- Reset REI configuration files
- Update Java to the recommended version
Understand that rei not fully initialized can occur due to memory starvation or aggressive optimization mods interfering with loading order.
Prevent the Error in the Future
Follow these best practices consistently:
- Always update mods together
- Avoid mixing loaders
- Add mods gradually
- Read mod compatibility notes
- Keep backups before updates
Prevention saves hours of troubleshooting later.
Frequently Asked Questions
Why does REI say not fully initialized but the game still runs?
Because REI fails during its final setup stage while Minecraft itself continues loading normally.
Is the error dangerous to my world?
No. The rei not fully initialized error does not corrupt worlds or save files.
Does this happen on both Fabric and Forge?
Yes. It occurs on both loaders when dependencies or compatibility fail.
Can I ignore the error?
No. Ignoring it means missing recipes, broken UI, and incomplete mod functionality.
Should I switch to JEI instead?
Only if the issue persists after proper troubleshooting. REI works reliably when configured correctly.
Final Thoughts
Fix the rei not fully initialized error by acting decisively. Update dependencies, remove conflicts, reload plugins, and test systematically. Treat REI as a dependency-driven system, not a standalone mod.
