ppy/osu · error · ArgumentOutOfRangeException

Unsupported animation style

Error message

Unsupported animation style

What it means

OsuModApproachDifferent.GetEasing() maps each AnimationStyle enum value to an Easing function used for approach-circle animation. The default case throws ArgumentOutOfRangeException for any enum value not covered, ensuring an unknown style is never silently assigned a default easing.

Source

Thrown at osu.Game.Rulesets.Osu/Mods/OsuModApproachDifferent.cs:87

                    return Easing.In;

                case AnimationStyle.Accelerate2:
                    return Easing.InCubic;

                case AnimationStyle.Accelerate3:
                    return Easing.InQuint;

                case AnimationStyle.Decelerate1:
                    return Easing.Out;

                case AnimationStyle.Decelerate2:
                    return Easing.OutCubic;

                case AnimationStyle.Decelerate3:
                    return Easing.OutQuint;

                default:
                    throw new ArgumentOutOfRangeException(nameof(style), style, @"Unsupported animation style");
            }
        }

        public enum AnimationStyle
        {
            Linear,
            Gravity,
            InOut1,
            InOut2,
            Accelerate1,
            Accelerate2,
            Accelerate3,
            Decelerate1,
            Decelerate2,
            Decelerate3,
        }
    }
}

View on GitHub (pinned to d9c73e12ad)

Solutions

1. Add a case for the new AnimationStyle value returning the appropriate Easing function.
2. If the enum is serialized/deserialized, validate the value against the known set before use.

Example fix

// before
case AnimationStyle.Decelerate3:
    return Easing.OutQuint;
default:
    throw new ArgumentOutOfRangeException(nameof(style), style, @"Unsupported animation style");

// after — add the missing case
case AnimationStyle.Decelerate3:
    return Easing.OutQuint;
case AnimationStyle.Accelerate4:
    return Easing.InCubic;
default:
    throw new ArgumentOutOfRangeException(nameof(style), style, @"Unsupported animation style");

// Validate the animation style before calling GetEasing
if (!Enum.IsDefined(typeof(AnimationStyle), style))
    throw new ArgumentOutOfRangeException($"Unknown animation style: {style}");

// Type guard for AnimationStyle exhaustiveness
static bool IsSupportedStyle(AnimationStyle style)
    => Enum.IsDefined(typeof(AnimationStyle), style)
        && style != (AnimationStyle)(-1);

When it happens

Trigger: A new AnimationStyle enum member is added without a corresponding case in GetEasing's switch, and the mod is configured with that style.

Common situations: Extending the approach-different mod with a new animation style but forgetting to add the easing mapping; enum deserialization producing a value outside the known set.

Related errors

• Unsupported grid type.
• Cannot Begin a rotate operation while another is in progress
• Cannot Update a rotate operation without calling Begin first
• Cannot Commit a rotate operation without calling Begin first
• Cannot Begin a scale operation while another is in progress!

AI-assisted analysis of ppy/osu@d9c73e12ad (2026-08-13). Data as JSON: /api/errors/4bab9beded5d6b87. Report an issue: GitHub.