Playing an animation in-game with extremely distant keyframes will freeze the game

Expected Behavior: The animation plays in game the same as it does the animation editor. (reversed easing bug aside.)
Actual Behavior: Game freezes, starts leaking memory like crazy.

Description: I made an animation for a model holding a sword. For this animation I wanted to hide the sword and was too lazy to hide the sword through code, so I made it disappear by creating keyframes where it is extremely far away (Granted, this is probably really dumb).
This method works just fine in the default animation editor plugin. Little did I know, this animation will cause an unrecoverable hang when played in game. The keyframes I created to hide the sword in particular are the cause.

Recreation Steps: (100% consistent)

  1. Open the repro place file in Studio.
  2. Go to the SwordDummy and click it with the Animation Editor open.
  3. Export the animation named “gamecrasher”. The problematic keyframes are the ones for the “BodyAttach”. Copy the animation ID.
  4. Place the copied animation ID in the animation object “IWillCrashYourGame”, parented to the script in the dummy. (See picture)

5. Play test the game. ~10 seconds later, Studio will hang.

To make it easier to see, I also have another animation in the dummy called “nocrasher”, which is the exact same animation without the BodyAttach keyframes. Using that animation instead, the game will not crash.

Example Video

Repro Place File:
t minus 10 seconds to crash.rbxl (50.6 KB)

Example Game: (To show this doesn’t only happen in studio.)

Issue Area: Engine
Issue Type: Animation
Impact: Low
Frequency: Constantly
Date First Experienced: 11/26/2021


Thanks for the report! We’ve filed a ticket to our internal database and we’ll follow up when we have an update for you.


Just wanted to update this with a small change in behavior: now Roblox Studio hangs when trying to load the problematic animation in the animation editor when it previously was able to load and edit it just fine.
Unfortunately this makes following the replication steps fully impossible since you won’t be able to load the animation to upload it yourself anymore.

Hello, apologies for the delay in updating this thread. We have fixed some issues since this was reported and we currently cannot repro the hang in either Studio or the Animation Clip Editor. We are resolving this for now, but please let us know if you are still experiencing this issue.

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