Diagnosing Packet Crashes and Lag with ViaVersion Debug Tools

Before you touch debug

/viaver debug prints every packet to the console. On a busy server this floods your log and can lag the server, so only enable it briefly and only when asked to by support.

Capturing a crash

1. Reproduce the problem with the affected player.

2. Run /viaver debug to start logging.

3. Have the player perform the action that crashes them (open a GUI, use an item, enter a chunk).

4. Run /viaver debug again to stop logging immediately.

5. Copy the relevant console section into your report. Include the player's client version from /viaver list.

Measuring load with /viaver pps

/viaver pps shows packets-per-second for ported players — those whose version differs from the server. A sudden spike usually means a plugin is spamming updates to a translated client, or a player is in a chunk-heavy area. Compare a ported player's number against a native-version player to see if translation is the bottleneck.

Reducing noise

• Run /viaver dontbugme to silence the update notifier if it clutters your console.
• Disable debug the moment you have your capture; leaving it on is the fastest way to fill a log file.