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Tickwise
CriticalPerformanceSIG-PA-006

Vanilla watchdog: a single tick took too long, the server was force-stopped

Platforms
Paper · Purpur · single server
Verified
Verified
Confidence
Confidence 95%

What it looks like in the log

Any one of these lines is enough. The agent matches them locally, on your server.

logs/latest.log
  • [WARN] A single server tick took

Symptoms

  • The server hung, then the process exited with a “Watching Server” crash report
  • In the log: “A single server tick took N seconds (should be max 0.05)”

Cause

The built-in vanilla watchdog (max-tick-time in server.properties) detected a tick longer than the limit and force-stopped the server. Paper/Spigot disable this watchdog — the message appears on vanilla-like builds and on forks that brought it back.

Possible causes

  • An infinite loop or a lock in a mod/plugin/datapack
  • A huge world operation or generation that exceeded max-tick-time
  • CPU starvation/a long GC pause

How to fixLow risk

  1. Open the crash report crash-reports/crash-<date>-server.txt (description “Watching Server”) and look at the Server thread stack — look for frames from a mod/plugin/datapack.
  2. Update or disable the component you find; check whether a heavy world operation was running at that moment.
  3. Do not disable max-tick-time (-1) as a fix: the server will hang instead of restarting.

Translated from the Russian original; log lines are quoted verbatim.

Sources