It looks like you’re encountering an assertion error during the animation import process, which likely points to an issue with the format or structure of your animation file. Here are a few steps you can try to resolve this:
Check the file format: Make sure your animation is in a supported format, such as FBX. Unreal Engine handles FBX files best, especially when exporting from tools like Blender, Maya, or 3ds Max.
Export settings: Double-check your export settings. When exporting animations, ensure that you’re exporting baked animation, that scale, position, and rotation keys are properly baked, and that you’ve included only deform bones (no extra controllers or rigs).
FBX version: Unreal Engine works best with FBX 2018 or FBX 2020. Try re-exporting your animation using one of these versions to see if it resolves the issue.
Interchange import system: Since the error mentions Interchange, try disabling the Interchange Import system and switch back to the legacy FBX Import system. You can do this in Project Settings → Plugins → Importers and disable the Interchange Plugin to revert to the older system.
Animation length & keys: Make sure the number of scale, position, and rotation keys matches across the entire animation. If they don’t, try re-baking the animation or cleaning it up in your 3D software.
Reimport and retry: If the issue persists, try importing the skeleton and mesh separately, then apply the animation after confirming the skeleton is properly set up.
If none of these steps work, please share more details about your animation file and the software you’re exporting from, so the community can assist further.