AntiCrashy

A server-side NeoForge mod for Minecraft 1.21.1 that helps keep your server online when mods misbehave.

What is AntiCrashy?

Minecraft servers don't always crash because of catastrophic failures. Sometimes all it takes is a single buggy mod throwing an exception in the wrong place. AntiCrashy acts as a safety layer between those failures and your server, catching common crash scenarios before they bring everything down.

Instead of waking up to a crashed server because one mod tried to load a client-only class or failed during an entity tick, AntiCrashy logs the problem, gathers diagnostic information, and lets the server continue running whenever possible.

It won't magically fix broken mods, but it can prevent many of them from taking your server offline.

Features

Event Exception Protection

Intercepts exceptions thrown by mod event handlers inside NeoForge's EventBus before they become fatal server crashes.

This specifically helps with issues such as:

• Client-only classes being loaded on dedicated servers
• RuntimeDistCleaner exceptions
• Event handler failures that would normally terminate the server

Entity Tick Protection

Wraps entity ticking in a safety layer so a single broken entity or modded tick handler can't immediately crash the entire server.

Watchdog Hang Detection

Monitors server tick times and detects hangs before the vanilla watchdog intervenes.

When a hang is detected, AntiCrashy:

• Tracks escalating warning levels
• Captures thread dumps automatically
• Records diagnostic information for later analysis

Thread Intervention

If the server becomes stuck, AntiCrashy attempts to identify blocking threads and take corrective action.

Depending on configuration, it can:

• Interrupt problematic threads
• Extend watchdog timeouts
• Attempt recovery procedures
• Trigger a controlled restart if recovery isn't possible

Advanced Diagnostics

AntiCrashy generates detailed troubleshooting data that goes far beyond standard Minecraft crash reports.

Diagnostics include:

• Full thread dumps
• Memory usage statistics
• Hang analysis reports
• Lock contention information
• Suspected mod involvement scoring

All reports are written to:

logs/anticrashy/

Player Notifications

Optionally notifies online players when the server is experiencing severe lag or recovery actions are being performed.

Automatic Restart Support

Includes an optional JVM shutdown hook that can automatically relaunch the server after any shutdown, helping reduce downtime.

Why This Exists

Certain mod combinations can trigger crashes that Minecraft and NeoForge handle poorly. A common example is a mod attempting to access a client-only class on a dedicated server, causing NeoForge's RuntimeDistCleaner to throw an exception. That exception propagates through the EventBus and ultimately crashes the server.

AntiCrashy operates at the point where these failures occur, allowing it to catch and suppress many non-critical exceptions before they become fatal.

The goal isn't to hide mod bugs—it's to keep your server running long enough for you to identify and fix them.

Installation

1. Download the AntiCrashy jar.
2. Place it in your server's mods/ folder.
3. Start the server.

No client installation is required.

Requirements

• NeoForge 1.21.1
• Java 21

Configuration

AntiCrashy uses the standard NeoForge configuration system.

You can customize:

• Hang detection thresholds
• Watchdog response behavior
• Player warning messages
• Diagnostic retention limits
• Automatic restart settings
• Individual protection features

Compatibility

AntiCrashy is completely server-side.

Players can join without installing the mod.

Logs and Diagnostics

When AntiCrashy detects a crash, hang, or recovery event, diagnostic information is written to:

logs/anticrashy/

If you're troubleshooting a problem, this should be the first place you look. The generated reports often make it much easier to identify the mod, thread, or system resource responsible for the issue than Minecraft's default crash reports.

Commands

AntiCrashy includes several administrative commands for monitoring server health, collecting diagnostics, and managing recovery actions in real time.

| Command | Description |
| ---------------------------------- | ------------------------------------------------------------------------------------------------------------------- |
| /anticrashy status | Displays live server status, including memory usage, thread counts, watchdog state, and active mitigation measures. |
| /anticrashy dump | Captures a complete diagnostic report, including thread dumps, memory statistics, and server state information. |
| /anticrashy interrupt <thread> | Interrupts a specific thread by name. Useful for dealing with blocked or runaway threads during server hangs. |
| /anticrashy config <key> <value> | Updates a configuration value without requiring a server restart. |
| /anticrashy restart [delay] | Schedules a safe server restart. An optional delay (in seconds) may be specified. |
| /anticrashy cancel | Cancels any pending AntiCrashy actions, including scheduled restarts and automated recovery operations. |

Permissions

All AntiCrashy commands require operator privileges (OP level 4) by default and are intended for server administrators.

(P.S: Thanks to Gattonori for giving me the idea to even make this mod <3)