[abenedik]

This error is thrown from the SelectAnimation method:

Code:

        public void SelectAnimation(string animationName)
        {
            if (animationName == null)
                throw new ArgumentNullException(nameof(animationName));

            var assimpAnimation = _assimpScene.Animations.FirstOrDefault(a => a.Name == animationName);

            if (assimpAnimation == null)
                throw new Exception("Cannot find animation with name " + animationName);

            SelectAnimation(assimpAnimation);
        }

As seen from the code, this error would be thrown when the SelectAnimation was called with the animationName parameter set to "Assimp.Animation" and when there was no animation in the _assimpScene.Animations with that name.

Please put a breakpoint into SelectAnimation and check where the value of animationName came from.