Minecraft invalid player data in singleplayer error: Possible fixes explored

Following the recent 1.21.4 update, Minecraft players have reported getting an "invalid player data" error, which prevents them from exploring the game's blocky world. The update has introduced a host of changes to functional aspects of the game, creating problems for players who enhanced their gameplay with mods and other add-ons.

This article lists possible fixes for the "invalid player data in singleplayer" error.

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Possible fixes for Minecraft invalid player data in singleplayer error

1) Update the mods

Update the mods to the latest version or downgrade the game (Image via Mojang Studios)

If you have Minecraft mods enabled, the latest 1.21.4 update to Fabric has rendered most mods obsolete and thus incompatible. This incompatibility has likely resulted in the "invalid player data in singleplayer" error.

Compatibility between mod loaders and mods is one of the most important aspects of customization, and this latest update has created an issue for players used to add-ons.

You can fix this problem by updating your mods to the latest 1.21.4 versions or by installing a downgraded version of the game to run the mods. If you wish to use your current mods with the latest The Garden Awakens update, you will have to wait until the creators of the add-on(s) update the assets to match compatibility with the latest title version.

Additionally, you can disable/remove all mods to clear the error. However, this will return your game to its original vanilla state.

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2) Disable mods and mod loaders

Disable all mods and mod loaders to ensure conflicts cease (Image via Mojang Studios)

Another method to resolve the "invalid player data in singleplayer" error is by disabling the mod you have installed. If you have multiple mods installed, you can disable them one by one to see if the issue is rectified.

Additionally, you can reinstall mod loaders such as Fabric, Forge, or NeoForge to fix corrupt files or potential issues. You should also check if any mods conflict with each other since a lot of add-ons have limitations when it comes to compatibility.

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3) Reinstall Minecraft

Reinstall the game as a final potential fix to the issue (Image via Mojang Studios)

If the above steps do not work, you can try reinstalling the game. Make sure to keep a backup of your world saves so that you can restore them by placing them in the saves folder.

Head to the Minecraft Launcher, select Java Edition, and delete the instance of the title creating issues. Then, reinstall the instance of the game and run it with your saved files restored as a potential fix to the "invalid player data in singleplayer" error.

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