VictoriaMetrics/VictoriaMetrics · error

cannot read metricName size: %w

Error message

cannot read metricName size: %w

What it means

Reading the 4-byte metricName size prefix failed with a non-EOF error mid-stream: the native payload ended abruptly or the reader errored between blocks.

Source

Thrown at lib/protoparser/native/stream/streamparser.go:68

	ctx := &streamContext{}
	for {
		uw := getUnmarshalWork()
		uw.tr = tr
		uw.ctx = ctx
		uw.callback = callback

		// Read uw.metricNameBuf
		if _, err := io.ReadFull(br, sizeBuf); err != nil {
			if err == io.EOF {
				// End of stream
				putUnmarshalWork(uw)
				ctx.wg.Wait()
				return ctx.err
			}
			readErrors.Inc()
			ctx.wg.Wait()
			return fmt.Errorf("cannot read metricName size: %w", err)
		}
		readCalls.Inc()
		bufSize := encoding.UnmarshalUint32(sizeBuf)
		if bufSize > 1024*1024 {
			parseErrors.Inc()
			ctx.wg.Wait()
			return fmt.Errorf("too big metricName size; got %d; shouldn't exceed %d", bufSize, 1024*1024)
		}
		uw.metricNameBuf = bytesutil.ResizeNoCopyMayOverallocate(uw.metricNameBuf, int(bufSize))
		if _, err := io.ReadFull(br, uw.metricNameBuf); err != nil {
			readErrors.Inc()
			ctx.wg.Wait()
			return fmt.Errorf("cannot read metricName with size %d bytes: %w", bufSize, err)
		}
		readCalls.Inc()

		// Read uw.blockBuf
		if _, err := io.ReadFull(br, sizeBuf); err != nil {

View on GitHub (pinned to 5079fb58f1)

Solutions

1. Re-export and re-upload the native data — the stream is truncated
2. Check network stability and proxy timeouts during upload
3. Confirm nothing appended extra bytes to the export file

When it happens

Trigger: Thrown at lib/protoparser/native/stream/streamparser.go:68 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of VictoriaMetrics/VictoriaMetrics@5079fb58f1 (2026-09-03). Data as JSON: /api/errors/35bb286547b05d77. Report an issue: GitHub.