Watchdog tick timeout (single server tick took)
Minecraft has a watchdog thread that monitors how long each server tick takes. If a tick runs longer than the configured threshold (default 60 seconds), the watchdog assumes the server has hung and forcibly shuts it down. The actual cause is usually a mod doing something expensive on the main thread — not a real freeze.
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How to fix it
- 1
Find the slow tick in the crash report
The watchdog crash dumps the stack of the main thread at the moment it killed the server. Look for any non-vanilla class names — that's the mod doing the heavy work. Common offenders: Lootr (entity reload), Cold Sweat (temperature recalculation), Better Spawners (chunk-wide scans).
- 2
Raise the watchdog timeout in server.properties
Set max-tick-time=-1 to disable the watchdog entirely, or max-tick-time=120000 (2 minutes) to give the slow tick room to finish. This treats the symptom, not the cause — use it while you investigate, not as the final fix.
- 3
Lower the offending mod's tick rate
Most heavy mods expose a config knob for how often they tick. Cold Sweat has a temperature tick rate (default 20, raise to 80). Lootr has a scan interval. Open the mod's config in config/ and find the relevant value.
- 4
Profile with spark to confirm
Run /spark profiler 30 in chat right after a hang. The resulting profile shows per-mod CPU time. Use it to verify which mod was the actual culprit, not just the one at the top of the stack.
Alternative causes
These can produce the same error message — worth ruling out if the steps above don't resolve it.
Disk write stall
If the world saves are slow (full disk, slow SSD, contended NFS), the save tick can exceed the watchdog. Check disk usage and IO health — symptom is intermittent watchdog kills with no consistent mod pattern.
GC pause storming
On under-allocated heaps, a Full GC can pause the JVM for 10+ seconds. If those land back-to-back during a single tick, the watchdog kills the server. Check our OutOfMemoryError guide for heap sizing.
Frequently asked
Is disabling the watchdog dangerous?
Not by itself — the watchdog only kills hung servers, it doesn't prevent crashes. Disabling it (max-tick-time=-1) means a truly hung server stays hung until you restart manually. Acceptable on small communities; less so on always-on hosted servers.
Why does it always happen at the same time of day?
Two common causes — daylight save mob-spawn waves trigger heavy entity ticks, and scheduled backups or world-saves can stall the save tick. Look at what's running at that time.
Can players cause a watchdog crash?
Yes — a player triggering a redstone-heavy contraption, opening a chest with thousands of items, or pasting a large WorldEdit selection can all spike a single tick past the threshold.
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Last reviewed 2026-06-05. If a step is wrong or out of date, tell us — we'll fix the article and the auto-pattern at the same time.