A Minecraft server calculates the world in ticks, 20 times per second. If a tick takes too long or the memory runs out, the server writes warnings to the log or, in the worst case, aborts. Each section below explains one of these messages: how to recognize it, how serious it is and what you can do. First come messages after which the server crashes or shuts down, then warnings where it keeps running.

You can find the full message in the Console or under Files in logs/latest.log, and crash reports in the crash-reports/ folder. Always read the lines before it too: they often show what slowed the server down. Before changing configuration or world files, create a backup under Backups.

“A single server tick took … seconds”: Watchdog shuts down the server

What the message looks like:

The server has not responded for <Seconds> seconds! Creating thread dump
A single server tick took 60.00 seconds (should be max 0.05)

What's behind it: The watchdog checks whether the server is still working. If a tick, one simulation step, takes too long, it shuts down the frozen server and gameplay stops. Paper first prints intermediate messages with a thread dump, a snapshot of ongoing work: if the server recovers in time, it continues running. Common causes are memory pressure or a heavy plugin or mod.

How to fix it:

  1. Under Files, read logs/latest.log before the first watchdog message. Check earlier errors; if Stopping server appears, also investigate what is blocking shutdown.
  2. Look at the top lines under Server thread in the dump. A plugin or mod name shows what last occupied the server.
  3. Check memory. OutOfMemoryError: Java heap space means Java's heap memory is exhausted; also check what is consuming it.
  4. Stop the server before changing files. Update the affected plugin under Plugins or mod under Mods, or remove it as a test, then restart and check again.

In detail: Properly fixing "Can't keep up" and watchdog timeouts

“Java heap space”: The server has run out of heap memory

What the message looks like:

An unexpected error while handling a WorldEdit command … java.lang.OutOfMemoryError: Java heap space
[LuckPerms] Thread <Thread> threw an uncaught exception … java.lang.OutOfMemoryError: Java heap space
failed to handle chunk data (write) … java.lang.OutOfMemoryError: Java heap space

What's behind it: Java manages server memory in an area called the heap, which has filled up under the current load. Large WorldEdit operations, many loaded chunks (world sections), modpacks or plugin data can consume memory. The server often crashes or becomes unstable; saving world or entity data, such as creatures and items, can also fail. The named thread or plugin shows where memory was unavailable, which may differ from the largest memory consumer.

How to fix it:

  1. Restart the server to end the exhausted process. With the same load, the error can return.
  2. Estimate memory needs: Planning Minecraft RAM requirements. If your plan is insufficient, choose more RAM under Settings & Plan → Plan.
  3. Split large WorldEdit operations and, if needed, lower view-distance under Files in server.properties.
  4. After restarting, check the Console and affected world areas. For chunk data (write) messages, check especially whether the latest changes were saved.

Good to know: A backup before your next major world change helps restore lost changes.

“This crash report has been saved to …”: Server crashed

What the message looks like:

This crash report has been saved to: crash-reports/crash-<Date>_<Time of day>-server.txt

What's behind it: The server was shut down by a hard error and wrote a crash report. The message itself only says where this report is located. The actual cause, such as a mod, a plugin, the world or missing memory, is in the file.

How to fix it:

  1. Under Files, open the crash-reports/ folder and the named file in it. Its name contains the date and time of the crash.
  2. Read the first section: after Description: there is a short description, followed by the error line and the stack trace, meaning the list of program locations that led to the error.
  3. Check the mods or plugins named in the error for compatible versions. Update the affected one under Mods or Plugins, or back up and temporarily remove it.
  4. For OutOfMemoryError, read its detail message. Java heap space means Java memory is full; if your plan has too little RAM, choose more under Settings & Plan → Plan.
  5. Start the server and watch the Console until it is fully running.

Good to know: Keep the report for troubleshooting and match its timestamp to the current crash. For mod servers: Mod errors on Forge, NeoForge and Fabric servers

Error in the main game loop

What the message looks like:

Exception in server tick loop
Caused by: java.lang.<Error type>: <Details>

What is behind it: The main loop calculates the world tick by tick. An exception, meaning a program error, has propagated into this loop and disrupted it. The server then usually crashes and writes a crash report. The actual cause is almost always in the Caused by line that follows directly.

How to fix it:

  1. Look for the message in logs/latest.log or in the newest report under crash-reports/.
  2. Read the Caused by line directly below it. If there are several, the lowest one usually leads to the root of the problem.
  3. The lines with at … below it name packages and files. From these you can identify the plugin or mod involved.
  4. Update or remove it under Plugins or Mods and restart the server.

Good to know: This message is not a lag problem but a specific error. More memory only helps if the Caused by line names an OutOfMemoryError.

In detail: Properly fixing "Can't keep up" and watchdog timeouts

Memory at its limit: GC overhead limit exceeded

What the message looks like:

java.lang.OutOfMemoryError: GC overhead limit exceeded

What is behind it: Java automatically cleans up memory that is no longer needed. This is called garbage collection, or GC for short. This message means: Java spends almost all its time cleaning up and hardly recovers any memory in the process. The heap, meaning Java's memory, is practically full. The server barely responds or crashes.

How to fix it:

  1. Restart the server.
  2. Determine how much memory your setup needs. In detail: Planning Minecraft RAM requirements
  3. If your package is not enough, choose more RAM under Settings & Plan → Plan.
  4. Reduce the chunk and entity load: lower the view distance view-distance in server.properties, shrink large animal farms and clean up items lying around.

Good to know: A restart only buys you some breathing room. If usage rises steadily to the limit after every restart even though the load stays the same, a plugin or mod may also be holding on to memory.

No new thread possible: unable to create native thread

What the message looks like:

java.lang.OutOfMemoryError: unable to create native thread

What is behind it: A thread is a parallel strand of work. Java tried to start another one and could not. Despite OutOfMemoryError in the name, this is not proof of a full Java heap. Usually too many threads are running at the same time, a process limit has been reached or memory outside the heap is missing. The server can then no longer start new tasks and becomes unstable. This line does not reveal which plugin or mod is creating the threads.

How to fix it:

  1. Do not simply book more RAM across the board. More memory for Java does not automatically solve this message.
  2. In logs/latest.log, read the lines before the message: what was running at the time of the error, which plugins were reporting frequently?
  3. Prove the culprit at runtime. With spark profiler start --thread * in the Console you can see all running threads. Their names often reveal the plugin or mod.
  4. Only once a culprit is proven do you update it under Plugins or Mods, check its settings or remove it.

If you get stuck, open a ticket and include the time of the message. On spark: spark: Finding and understanding lag

“Can't keep up”: Server ticks are falling behind

What the message looks like:

Can't keep up! Is the server overloaded? Running 2014ms or 40 ticks behind

What's behind it: Minecraft normally runs 20 ticks per second, giving each tick a time budget of 50 milliseconds. If these processing steps take too long, a backlog builds up, reported in milliseconds and ticks. The server keeps running but noticeably slower: mined blocks reappear and mobs stutter. Memory or CPU pressure is usually responsible; isolated messages can occur during startup or terrain generation.

How to fix it:

  1. Check whether spark is available. Current Paper versions include it; on other supported servers, install the matching plugin or mod release.
  2. Run spark tps in the Console during the lag. MSPT means milliseconds per tick: if ticks consistently exceed their time budget, the tick rate drops.
  3. Find the cause with spark profiler start --timeout 120 and open the link returned afterwards.
  4. With the server stopped, lower view-distance and simulation-distance in server.properties. Reduce large farms or pregenerate the world.
  5. Check whether memory is sufficient, and restart after configuration changes.

In detail: Properly fixing "Can't keep up" and watchdog timeouts

“DO NOT REPORT THIS TO PAPER”: Diagnostics during a server stall

What the message looks like:

--- DO NOT REPORT THIS TO PAPER - THIS IS NOT A BUG OR A CRASH ---
Server thread dump (Look for plugins here before reporting to Paper!):

What's behind it: If the server thread hangs for a few seconds, Paper writes a diagnostic with a thread dump, meaning a snapshot of what the server is currently working on. Gameplay stalls while this happens; the server can continue once it recovers. If the blockage lasts too long, the watchdog shuts it down.

How to fix it:

  1. In the dump, read the top lines under Server thread dump. If a plugin or mod name appears there, it is a strong hint at the culprit.
  2. Stop the server, update the affected plugin under Plugins or mod under Mods, or remove it as a test, then restart.
  3. If the dumps pile up, check the memory, your plugins and the view distance view-distance in server.properties.
  4. Isolated dumps, for example at startup or when saving a large world, you can simply observe instead of intervening right away.

In detail: Properly fixing "Can't keep up" and watchdog timeouts

“ChunkTaskScheduler”: Paper is waiting for a chunk to load or generate

What the message looks like:

[ChunkTaskScheduler] Chunk wait task info below:
[ChunkTaskScheduler] Chunk holder: NewChunkHolder{world=<World>, chunkX=<x>, chunkZ=<z>, …, currentGenStatus=minecraft:initialize_light, requestedGenStatus=minecraft:full, …}

What's behind it: Paper waited longer than expected for a chunk, a 16 × 16 block world section, to load or generate and wrote a diagnostic. The server stalls at that moment. currentGenStatus shows progress; requestedGenStatus shows the target. Overload is common: world generation, players spread far apart or slow plugins. A damaged region is another possible cause.

How to fix it:

  1. Under Files, lower view-distance in server.properties and restart.
  2. Pregenerate the world: Chunky: Pregenerating a Minecraft world.
  3. If spark is available, profile during the problem with spark profiler start --timeout 120 in the Console. The report shows which operations consume time.
  4. If the same world and chunk coordinates recur, check surrounding log lines for region loading errors. For confirmed damage, stop the server, save its current state and restore an intact backup under Backups. Changes made since that backup will be lost.

Good to know: Very large coordinates suggest travel far from the world centre. A suitable world border limits further exploration.

“The server has stopped responding”: Paper watchdog detects a stall

What the message looks like:

The server has stopped responding! This is (probably) not a Paper bug.
If you see a world save or edit, then it means you did far more than your server can handle at once
If this is the case, consider increasing timeout-time in spigot.yml but note that this will replace the crash with LARGE lag spikes

What's behind it: These lines belong to the Paper watchdog's notice block for a blocked main thread, the worker responsible for gameplay. Gameplay stalls during the hang; if the blockage persists, the watchdog stops the server. Typical causes are overloaded plugins, large world operations or blocking HTTP and database calls. The thread dump below lists the program calls being executed.

How to fix it:

  1. Read the thread dump in logs/latest.log under Files. Check named plugins for updates; adjust their configuration or remove them temporarily while the server is stopped.
  2. If it shows world editing or saving, split large actions, such as WorldEdit operations, into smaller steps.
  3. For HTTP or MySQL calls, check the plugin's connection and the service's availability.
  4. Raising timeout-time in spigot.yml extends the wait but leaves the blockage unresolved.
  5. For repeated hangs, reduce plugin load and check memory.

In detail: Properly fixing “Can't keep up” and watchdog timeouts

Paper chunk task fails with BootstrapMethodError

What the message looks like:

[ca.spottedleaf.concurrentutil.executor.thread.BalancedPrioritisedThreadPool] Exception thrown from thread <Thread>
java.lang.BootstrapMethodError: bootstrap method initialization exception

What is behind it: Paper loads and generates chunks in its own threads, meaning parallel strands of work alongside the main game. In one of them, Java could not prepare a call site in the program. Possible reasons are a bug in Paper, an incompatible extension or an unsupported Java version. The message alone does not pinpoint any of these causes.

How to fix it:

  1. Update Paper under Version to a current stable build of your Minecraft version.
  2. Use a Java version that this build supports: Which Java version does your Minecraft server need?
  3. Read the full stack trace in logs/latest.log. If a Caused by line names a plugin, update it under Plugins.
  4. Do not swap server libraries by hand. That is more likely to cause new errors.
  5. If the error occurs repeatedly after the update, report the full stack trace to the Paper project.

Minecraft cannot save the crash report

What the message looks like:

We were unable to save this crash report to disk.

What's behind it: This message concerns writing the crash report. After an error, Minecraft tried to save diagnostic information to disk but could not write the report file. Earlier Console output contains the original error; the missing report makes later troubleshooting harder.

How to fix it:

  1. First preserve the complete error block from the Console, including the lines preceding this message.
  2. Under Files, inspect existing files in crash-reports/ and logs/latest.log. Read the specific write error and check available storage.
  3. Resolve the stated cause. If the path remains unwritable, open a ticket and include the timestamp and write error.

Your message isn't listed?

Read the entire message in logs/latest.log and above all the lines before it: overload almost always has a trigger that comes before the first warning. In the stack trace or thread dump, package names, meaning the folder names separated by dots such as com.<Developer>.<Plugin>, and file names such as <Plugin>.jar reveal which plugin or mod is involved. Before changing configuration files, create a backup under Backups. If you get stuck, open a ticket and include the time of the message.

You can order a matching server here: Rent Minecraft server.