How to Fix “An Error Occurred in e4mc” in Minecraft: Full Troubleshooting Guide

Last updated on August 24th, 2025 at 05:26 pm

Getting “An error occurred in e4mc” in Minecraft? This guide explains why the error happens, what causes it, and how you can fix it step by step. By the end, you will know how to troubleshoot relay problems, handle mod conflicts, and use reliable alternatives if needed.

What is e4mc?

e4mc (Easy 4 Minecraft) is a mod that lets you share local Minecraft worlds across the internet using public LAN links. It connects through relay servers so that your friends can join even if they are not on the same network.

However, many players run into the error “An error occurred in e4mc” when opening their worlds to LAN. This happens for several reasons, from server outages to conflicting mods. Understanding the root causes makes fixing it much easier.

Root Causes of the e4mc Error

The error does not always come from the same source. Common causes include:

1. Relay Server Connectivity Failures

• Regional relays, especially in North America, may go offline.
• QUIC protocol handshakes can silently fail.
• High latency from certain regions can block connections.

Example Log:

[20:07:51] [nioEventLoopGroup-2-1/INFO]: [CHAT] An error occurred in e4mc
java.lang.RuntimeException: null
at link.e4mc.QuiclimeSession.lambda$start$4(QuiclimeSession.java:328)

2. Mod Conflicts and Compatibility Problems

• Performance mods such as Sodium, Lithium, or C2ME
• Network-altering mods like NoChatReports
• Version mismatches between Fabric API, e4mc, and Minecraft

3. Broken QUIC Protocol Implementation

• Netty QUIC errors (DefaultPromise, QuicheQuicChannel) can disrupt relay connections.

4. Offline Mode and Authentication Failures

• Using cracked clients or PrismLauncher may trigger:

com.mojang.authlib.exceptions.InvalidCredentialsException: Status: 401

• Without Mojang authentication, the relay setup fails.

Quick Troubleshooting Overview

Before we go step by step, here is a quick overview of issues and their immediate fixes:

Issue	Likely Cause	Quick Fix
Relay not working	Regional downtime	Switch to EU/NA relay
Mods breaking e4mc	Sodium / NoChatReports	Run clean setup with only e4mc
Java mismatch	Old Java version	Update to Java 17
Authentication failure	Cracked client	Use Mojang/Microsoft login
ISP blocking relay	NAT/Firewall	Try Playit.gg / Ngrok / ZeroTier

Now, let’s walk through the full fixes step by step.

How to Fix “An Error Occurred in e4mc” (Step-by-Step Guide)

Step 1: Check Relay Server Status

1. Visit status. e4mc.link.
2. If servers are down, wait and try again later.
3. If possible, switch relay regions (for example, from NA to EU).

Relay issues are the most common reason for this error, and switching regions often solves the problem.

Step 2: Run a Clean Mod Setup

1. Open your .minecraft/mods folder.
2. Keep only:
   • e4mc (latest version)
   • Fabric Loader and Fabric API
3. Remove mods such as Sodium, Lithium, NoChatReports, or EnhancedBlockEntities.
4. Restart Minecraft and test again.

This ensures no other mods interfere with how e4mc connects.

Step 3: Update Java and Adjust System Settings

• Install Java 17 (recommended for e4mc).
• In your launcher settings, allocate memory:

-Xmx4G -Xms2G

• Temporarily disable firewall or antivirus blocking javaw.exe.
• Test using a different connection, such as switching from WiFi to a mobile hotspot.

Updating Java and adjusting these settings removes version conflicts and network blocks.

Step 4: Inspect Logs for Errors

1. Open .minecraft/logs/latest.log.
2. Look for error lines such as:
   • QuiclimeSession.java
   • InvalidCredentialsException
   • DefaultPromise.setFailure
3. Save the log and your mod list.
4. Report the issue at e4mc GitHub Issues.

Sharing logs helps developers confirm whether the issue lies with your setup or with e4mc itself.

Step 5: Use Alternatives if e4mc Still Fails

If e4mc continues to fail, consider using other tools:

• Playit.gg – beginner-friendly, creates a public relay tunnel.
• Ngrok – secure tunnel, free plan resets every two hours.
• ZeroTier VPN – virtual LAN, works even through NAT or firewalls.

These options work as reliable substitutes when relay servers are unstable.

Advanced Tips for Resolving e4mc Errors

For advanced users, the following methods can help improve stability and reliability:

1. Custom Relay Configuration

Force e4mc to use a specific relay region by editing its configuration file:

e4mc.relay.region=eu

Switching to European relays often improves stability when North American servers are overloaded.

2. Version Compatibility Matrix

Different combinations of e4mc, Fabric API, and Java work more reliably together.
Here are tested setups:

e4mc Version	Fabric API	Java
5.2.1	0.85.0	17
5.3.0	0.92.0	17

Avoid experimental Fabric builds unless they have been tested with e4mc.

3. Clean Mod Environment Setup

When updating or troubleshooting:

• Fully delete .minecraft/mods and config folders related to e4mc.
• Reinstall only required dependencies.
• Do not import old configuration files, as they may carry corrupted settings.

4. Advanced Network Workarounds

If your ISP or firewall blocks relay traffic, you can bypass it with tunneling tools:

• Ngrok – tunnels your LAN port through a public endpoint.
• Playit.gg – lightweight relay service with free public links.
• ZeroTier VPN – creates a virtual LAN that works even through NAT or strict firewalls.

These tools can temporarily replace e4mc if relay outages last for weeks.

Developer Notes

Most reported issues point to QuiclimeSession.java during relay setup.
Likely causes include:

• Null handling problems
• Relay timeouts not being caught
• Silent QUIC disconnects

Suggested improvements include retrying across regions, adding fallback logic, and giving clearer in-game error messages.

Read More: How to Fix Minecraft Error Code B-0010 on Nintendo Switch

The error “An error occurred in e4mc” usually comes down to relay server problems, mod conflicts, or Java version mismatches. In most cases, you can resolve it by switching relay regions, running a clean setup, and updating to Java 17. If nothing works, tools like Playit.gg and Ngrok provide practical alternatives. By following these steps and, if needed, reporting logs to developers, you can get your Minecraft LAN worlds running smoothly again.