ppy/osu · error · InvalidDataException

Unknown event type: {split[0]}

Error message

Unknown event type: {split[0]}

What it means

Thrown by LegacyStoryboardDecoder.handleEvents when a line in the [Events] section (at depth 0, i.e. not a sub-command) has a first token that doesn't parse to a LegacyEventType enum value. The decoder uses Enum.TryParse on the token, and anything not matching a known event name (Background, Video, Sprite, Animation, Sample, etc.) triggers this.

Source

Thrown at osu.Game/Beatmaps/Formats/LegacyStoryboardDecoder.cs:117

            foreach (char c in line)
            {
                if (c == ' ' || c == '_')
                    depth++;
                else
                    break;
            }

            line = line.Substring(depth);

            string[] split = line.Split(',');

            if (depth == 0)
            {
                storyboardSprite = null;

                if (!Enum.TryParse(split[0], out LegacyEventType type))
                    throw new InvalidDataException($@"Unknown event type: {split[0]}");

                var source = isPrimaryStream ? StoryboardElementSource.Beatmap : StoryboardElementSource.Shared;

                switch (type)
                {
                    case LegacyEventType.Background:
                    {
                        // the actual filename is handled in `LegacyBeatmapDecoder`.
                        // this only handles the background offset, because it does not logically belong in `Beatmap` or related classes.
                        if (split.Length > 4)
                        {
                            float x = Parsing.ParseFloat(split[3]);
                            float y = Parsing.ParseFloat(split[4]);
                            storyboard.BackgroundOffset = new Vector2(x, y);
                        }

                        break;
                    }

View on GitHub (pinned to d9c73e12ad)

Solutions

1. Open the file in a text editor, go to the [Events] section, and find the line whose first field is shown in the error message.
2. Correct the event keyword to a valid LegacyEventType (Background, Video, Sprite, Animation, Sample).
3. If the event type is genuinely new/unknown, either remove the line or update the LegacyEventType enum and add handling.
4. Re-download the beatmap/storyboard if it's corrupt.

try
{
    storyboardDecoder.Decode(reader);
}
catch (InvalidDataException ex) when (ex.Message.Contains("Unknown event type"))
{
    Logger.Log($"Unrecognized storyboard event — skipping or rejecting file: {ex.Message}", LoggingTarget.Database);
}

When it happens

Trigger: Decoding a .osu or .osb file whose [Events] section contains a line with an unrecognized event keyword — e.g. 'UnknownEvent,0,0,...'. Typos like 'Backgroudn' or entirely custom event types not in the LegacyEventType enum cause the parse to fail.

Common situations: A storyboard produced by a non-standard editor that emits event types not in the osu! specification; manual editing with a typo in an event keyword; a future/corrupt format version with new event types the current decoder doesn't know.

Related errors

• Unknown command type: {commandType}
• Beat length cannot be NaN in a timing control point
• Color specified in incorrect format (should be R,G,B or R,G,
• Color must be specified with 8-bit integer components

AI-assisted analysis of ppy/osu@d9c73e12ad (2026-08-13). Data as JSON: /api/errors/79d91e9a4203f824. Report an issue: GitHub.