What carries over
A Java Edition world stores each player under their UUID, not their name. After a rename, all of this still belongs to the player:
- Inventory, position and health, saved in the world’s
playerdatafolder. - Statistics and advancements, in the
statsandadvancementsfolders. - Entries in
whitelist.json,ops.jsonandbanned-players.json. The name stored next to the UUID in these files can be out of date, but access is decided by the UUID. - Pets, which remember their owner by UUID.
What doesn’t follow the player
| Thing | What happens |
|---|---|
| Scoreboard scores | Players’ scores are stored by name, so the old scores stay under the old name and the new name starts from zero. |
| Team membership | Teams list players by name. The renamed player has to be added to the team again. |
| Commands and command blocks | Anything that targets the old name, like /tp OldName in a command block, stops matching. |
| Text in the world | Signs, books and item names still show whatever was written, including the old name. |
| Plugins | Most plugins store UUIDs. Older or badly written ones that store names lose track of the player. |
When a rename does lose data
On a server with online-mode=false, the UUID is calculated from the name. A new name gives a new UUID, so the server sees a brand new player: empty inventory, spawn point, no whitelist entry. The old data is still in the world folder under the old UUID, but it isn’t loaded.
The same happens if the player only changes the capitalisation of their name, because the calculation uses the exact name.
Name change rules
- Names are changed on the player’s profile at minecraft.net.
- A Java Edition name can be changed at most once every 30 days.
- Names are 3 to 16 characters long and use letters, numbers and underscores. Some accounts from the game’s early days have shorter names.
Checking who someone is now
If you only have an old name, it may belong to a different account by now. Look up a known UUID in the UUID Lookup instead: it always returns the account’s current name. Previous names can’t be looked up, because Mojang removed public name history in 2022.