Minecraft Exception in Server Tick Loop

Your Minecraft server crashes, and the console shows “Exception in Server Tick Loop.” The error tells you the server failed during its tick cycle, but it doesn’t tell you why. Every 20th of a second, the server runs a tick: processing player movement, mob AI, block updates, and game logic. When something breaks that cycle hard enough, the whole server goes down. The crash report is long, technical, and often points at unfamiliar code. This guide walks you through the most common causes and the fastest fixes.

What Causes the Exception in Server Tick Loop?

Corrupted or invalid JSON configuration files are the leading cause of this crash. Every Minecraft server keeps several JSON files in its root directory to track which players are banned, opped, whitelisted, and cached. A single missing bracket, an extra comma, or an invalid character in any of these files is enough to bring the server down on startup.

When JSON corruption is the cause, your crash report will include a line like com.google.gson.stream.MalformedJsonException. This points directly at a broken JSON file. The report won’t always name the specific file, which is why deleting all five at once is the fastest solution.

Other causes include:

• Mod or plugin conflicts: two mods modifying the same game system can throw a NullPointerException during a tick. If an unfamiliar package name appears near the top of your stack trace (something like com.authorname.modname), that mod is the likely culprit.
• Corrupted world chunks: a damaged chunk can cause a ticking entity or block error. The crash description may say “Ticking block entity” or “Ticking entity” rather than “Exception in server tick loop” in those cases.
• In-game tick overload: excessive redstone, too many entities in a small area, or runaway mob farms can sometimes push a tick to failure under heavy load.

This crash appears on Forge, Fabric, Spigot, Paper, and Vanilla servers. The cause varies by server type, which is why reading the crash report is the first step toward a solution.

How to Read the Crash Report

Every crash drops a file in the crash-reports folder inside your server’s FTP. You can also review the console output directly. Knowing how to read the report saves time before you start deleting files. You can learn more in the Apex Hosting guide to reading Minecraft crash reports.

Description line: the first section of the report. It tells you what the server was doing when it crashed. “Exception in server tick loop” confirms this is a tick-cycle failure, not a startup config problem.

Stack trace: the block of text starting with java.lang or com.google. Read it top to bottom. The first line names the error type:

• MalformedJsonException: broken JSON file. Go straight to the fix below.
• NullPointerException: something expected data that wasn’t there. Check the next few lines for a mod or plugin package name.
• StackOverflowError: infinite loop, often from a mod or plugin conflict.

System information: the bottom section lists your Minecraft version, Java version, and all loaded mods. Cross-reference mod names here against what you saw in the stack trace.

If you cannot identify the cause from the report, contacting the Apex Hosting Support Team is the fastest path to a resolution.

How to Fix ‘Exception in Server Tick Loop’

If your crash report shows a JSON error, or if you recently edited any of the server’s JSON files manually, delete and regenerate them. The server recreates these files on startup with clean defaults.

1. Head towards your Apex server panel, then click FTP File Access near the top left.
   

2. Use your credentials to login, then check mark the following files: banned-ips.json, banned-players.json, ops.json, usercache.json, whitelist.json.
   

3. Proceed to click the Delete at the top, then click the Submit button when prompted.
   

4. Return to the main panel and Restart the server to regenerate these files.

Before deleting, download the files if you need to preserve your ban list, op list, or whitelist. After the server restarts, use console commands to restore those entries: /op, /ban, /whitelist add, and /ban-ip.

If the server still crashes after regenerating the JSON files, the cause is something else. Move on to mod conflict troubleshooting below.

Troubleshooting Mod and Plugin Conflicts

When the stack trace points at a mod or plugin rather than a JSON file, the troubleshooting process is different. These steps work for Forge, Fabric, Spigot, and Paper servers.

Step 1: Identify the mod in the stack trace. The package name in the trace (e.g., com.authorname.modname) usually matches a specific mod’s ID. Cross-reference it against your mod list in the system information section of the crash report.

Step 2: Update the mod. Version mismatches and missing dependencies account for a large share of mod-related crashes. Check the mod’s page on CurseForge or Modrinth for the latest version compatible with your server type and Minecraft version.

Step 3: Bisect the mod list. If updating doesn’t resolve it, remove half your mods and restart. If the crash stops, the problem is in the removed half. Add mods back in batches until the crash returns. This narrows the conflict to a specific mod or pair of mods.

Step 4: Check for dependency conflicts. Some mods require specific versions of library mods (like Architectury, Kotlin for Forge, or Cloth Config). A version mismatch in a dependency can crash the server even if the main mod is up to date.

For modded servers, the Minecraft Modded Server Optimizations Guide covers additional configuration steps that can prevent tick overloads and reduce the risk of mod-related crashes.

Preventing Server Tick Loop Crashes

Most JSON-related crashes are preventable. Never edit banned-ips.json, banned-players.json, ops.json, usercache.json, or whitelist.json by hand. Use console commands instead: /op [player], /ban [player], /ban-ip [ip], /whitelist add [player]. These commands write valid JSON automatically.

For mod-related crashes, keep your mod list updated and test new mods on a local copy before adding them to a live server. Keeping a backup of your server before major mod updates gives you a fast rollback option if something goes wrong.

General server optimization also reduces crash risk. A server running close to its performance limits is more vulnerable to tick failures. The Minecraft Server Optimization Guide covers view distance, entity limits, and other settings that keep your server stable.

If you run into a related error where a single entity is causing the crash, the guide on fixing the Ticking Entity crash in Minecraft covers that specific case.

Exception in Server Tick Loop: FAQ

The most common cause is a corrupted or invalid JSON configuration file, specifically one of five files the server uses to track bans, ops, and whitelisted players. Mod conflicts, corrupted world chunks, and tick overload from excessive entities or redstone can also trigger this crash.

All crash reports are saved to the crash-reports folder in your server’s FTP directory. The console also shows crash output in real time when the server goes down.

If the crash report shows a JSON error, delete the five JSON config files via FTP and restart. The server regenerates them with clean defaults. If the crash trace points at a mod or plugin, update that mod or bisect your mod list to isolate the conflict. Reach out to the Apex Hosting Support Team if neither fix resolves it.

Yes, your ban list, op list, and whitelist are cleared. Download the files before deleting them if you need to preserve that data, and use console commands to reinstate players after the server restarts.

Yes. Use console commands (/op, /ban, /whitelist add) instead of manually editing JSON files. Keep mods updated and test changes on a local copy first. Optimizing your server’s entity limits and view distance also reduces the risk of tick-related crashes.

If the server still crashes after regenerating the JSON files, the cause is a mod conflict, a corrupted world chunk, or another configuration issue. Open the crash report and look at the stack trace for a mod package name or a different error type like NullPointerException. The Apex Hosting Support Team can help identify the root cause if the trace isn’t clear.