# Diagnose a MythicMobs boss bar that disappears during combat

A boss bar can disappear while the entity remains alive. Check its visibility rules and encounter transitions before replacing the mob or resetting the arena.

## Check the installed content

MythicMobs separates mob definitions, skills, targeters and triggers. Keep the internal IDs stable while testing a behaviour change; changing a display name does not require replacing the mob ID. Use documentation for your installed MythicMobs release.

## Work through the change

1. Record the boss internal ID, entity health and whether all players lose the bar or only players at a particular distance. Use a test copy of the encounter.
2. Compare the boss-bar section with the mob reference for the installed release. Keep a copy of the existing title, range and display settings before editing them.
3. Remove optional visibility conditions from the staging variant one at a time. Test close to the boss, at the arena edge and after leaving and re-entering the area.
4. Follow any phase transition that replaces or transforms the boss. Confirm that the new entity or definition also has the required display configuration.

## Verify the result

The intended players should see a consistent bar for the active boss entity, with a health display that follows the encounter. A replacement phase should create the expected new bar rather than leaving an old one behind.

## If the result differs

If only one client fails, compare client-side display behaviour before editing the server definition. If everyone fails at the same phase, inspect the entity replacement and skill log at that timestamp.

## Keep a recovery path

Reinstate the previous bar section while keeping the working combat logic. Do not delete live bosses to repair a cosmetic display; plan a controlled encounter reset if the entity itself needs replacement.

## References and related help

Check the maintainer reference: [MythicMobs documentation](https://wiki.mythiccraft.io/mythicmobs/Mobs/Mobs).

Before changing live data, read [how to keep a completed recovery copy](https://help.cloudexa-hosting.com/books/game-hosting/page/back-up-game-files-before-making-changes). For startup errors, use [the log collection guide](https://help.cloudexa-hosting.com/books/game-hosting/page/find-minecraft-logs-and-send-useful-troubleshooting-details).