If you are downloading from a third-party link sent by a friend or found in a Discord server, ensure the file name ends in .mcpack or .mcaddon.
Minecraft Bedrock Edition 1.21 introduced significant changes to the game’s engine, specifically regarding how the player entity is rendered and how animations are handled in code.
Most addons rely on "player.json" files to override vanilla behaviors. When Mojang updates the game, they change the structure of that file. If the addon tries to force an old structure onto the new game, the game says "Nope," and either crashes or disables the mod. descargar action stuff para minecraft bedrock 121 fix 90
The version you are seeing labeled "fix 90" usually refers to a patched version of the addon optimized for the newer rendering engines (often related to specific render dragon fixes or version build numbers in the modding community).
Before you click any random link promising a download, a word of caution: Beware of scams. Many sites claiming to have "Action Stuff Fix 121" are actually clickbait or ad-farms. If you are downloading from a third-party link
Here is the safe route to getting your movement back:
Official / recommended:
Important: Avoid random ".exe" files or shady adfly links. Bedrock add-ons should be .mcaddon or .mcpack.