TeamNewPipe/NewPipe · error · RuntimeException

Cluster element found without Info and/or Tracks element at…

Error message

Cluster element found without Info and/or Tracks element at position {}

What it means

Thrown by WebMReader when parsing a Matroska/WebM Segment element: the parser encountered a Cluster (the media-data container) before it saw the required Info and/or Tracks metadata elements. In a well-formed WebM file the Info element (codec/duration/timecode-scale metadata) and Tracks element (stream descriptions) must precede the first Cluster. The reader only sets metadataExpected when it knows the segment is not a live stream, so this fires on structurally invalid or truncated files where the metadata section is missing or was cut off before the Cluster began.

Solutions

1. Validate the source file is complete and well-formed before feeding it to WebMReader (check download finished, file size matches expected Content-Length).
2. Re-download or re-extract the stream: the metadata section was missing or truncated, indicating the source file is damaged.
3. If reading a live stream or segment that legitimately omits metadata, construct the reader so metadataExpected is false (the overload that knows this is a continuation/live segment).
4. Catch the RuntimeException at the call site and surface a user-facing 'media file is corrupt' message rather than crashing.

Example fix

// before — crashes on truncated downloads
WebMReader reader = new WebMReader(stream);
Segment segment = reader.parse();

// after — guard against corrupt/truncated media
try {
    WebMReader reader = new WebMReader(stream);
    Segment segment = reader.parse();
} catch (RuntimeException e) {
    if (e.getMessage().contains("Cluster element found without")) {
        throw new IOException("Corrupt WebM file: missing Info/Tracks metadata", e);
    }
    throw e;
}

// Verify the WebM stream has Info and Tracks before the first Cluster
// by doing a lightweight EBML pre-scan, or check file completeness:
if (streamFile.length() < minExpectedSize) {
    throw new IOException("WebM source too small / likely truncated: " + streamFile.length());
}

try {
    WebMReader reader = new WebMReader(stream);
    Segment seg = reader.parse();
} catch (RuntimeException e) {
    if (e.getMessage() != null && e.getMessage().contains("Cluster element found without")) {
        // treat as corrupt/incomplete source — re-download or skip
        throw new IOException("Corrupt WebM: missing Info/Tracks metadata", e);
    }
    throw e;
}

When it happens

Trigger: readSegment() is called with metadataExpected=true; the while-loop breaks on the first ID_CLUSTER element (line 278-281) before both obj.info and obj.tracks are populated; the post-loop check at line 293 finds one or both null and throws. This happens when the stream's Segment starts directly with a Cluster, or when Info/Tracks appear after the Cluster instead of before it.

Common situations: Downloading a truncated or partially-written WebM/Opus audio file (e.g. download interrupted mid-write); receiving a live DASH/HLS WebM adaptation that omits the head metadata when saved; a remuxing tool that reordered EBML elements incorrectly; corrupt media cache left over from a failed download.

Related errors

• Cluster at without Timecode element
• Unexpected SimpleBlock element size, missing
• cannot get the audio sample rate
• Element Timecode not found
• expected found

AI-assisted analysis of TeamNewPipe/NewPipe@9e8be09156 (2026-08-14). Data as JSON: /api/errors/3e41ae2df87970f6. Report an issue: GitHub.

Appendix: source

Thrown at app/src/main/java/org/schabi/newpipe/streams/WebMReader.java:294

        Element elem;
        while ((elem = untilElement(ref, ID_INFO, ID_TRACKS, ID_CLUSTER)) != null) {
            if (elem.type == ID_CLUSTER) {
                obj.currentCluster = elem;
                break;
            }
            switch (elem.type) {
                case ID_INFO:
                    obj.info = readInfo(elem);
                    break;
                case ID_TRACKS:
                    obj.tracks = readTracks(elem, trackLacingExpected);
                    break;
            }
            ensure(elem);
        }

        if (metadataExpected && (obj.info == null || obj.tracks == null)) {
            throw new RuntimeException(
                    "Cluster element found without Info and/or Tracks element at position "
                            + ref.offset);
        }

        return obj;
    }

    private WebMTrack[] readTracks(final Element ref, final int lacingExpected) throws IOException {
        final ArrayList<WebMTrack> trackEntries = new ArrayList<>(2);
        Element elemTrackEntry;

        while ((elemTrackEntry = untilElement(ref, ID_TRACK_ENTRY)) != null) {
            final WebMTrack entry = new WebMTrack();
            boolean drop = false;
            Element elem;
            while ((elem = untilElement(elemTrackEntry)) != null) {
                switch (elem.type) {
                    case ID_TRACK_NUMBER:

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