nats-io/nats-server · error

processRoutedOriginClusterMsgArgs Bad or Missing Header Size

Error message

processRoutedOriginClusterMsgArgs Bad or Missing Header Size: '%s'

What it means

After parsing, the header-size token of the routed origin-cluster message produced a negative value via parseSize — i.e. the token could not be parsed as a non-negative size (parseSize returns -1 on failure). The offending raw argument line is echoed. Causes: non-numeric header size field or a protocol/version mismatch shifting field positions.

Source

Thrown at server/route.go:262

		}

		// Grab header size.
		c.pa.hdb = args[len(args)-2]
		c.pa.hdr = parseSize(c.pa.hdb)

		// Grab size.
		c.pa.szb = args[len(args)-1]
		c.pa.size = parseSize(c.pa.szb)

		// Grab queue names.
		if c.pa.reply != nil {
			c.pa.queues = args[5 : len(args)-2]
		} else {
			c.pa.queues = args[4 : len(args)-2]
		}
	}
	if c.pa.hdr < 0 {
		return fmt.Errorf("processRoutedOriginClusterMsgArgs Bad or Missing Header Size: '%s'", arg)
	}
	if c.pa.size < 0 {
		return fmt.Errorf("processRoutedOriginClusterMsgArgs Bad or Missing Size: '%s'", args)
	}
	if c.pa.hdr > c.pa.size {
		return fmt.Errorf("processRoutedOriginClusterMsgArgs Header Size larger then TotalSize: '%s'", arg)
	}

	// Common ones processed after check for arg length
	c.pa.origin = args[0]
	c.pa.account = args[1]
	c.pa.subject = args[2]
	if len(an) > 0 {
		c.pa.pacache = c.pa.subject
	} else {
		c.pa.pacache = arg[len(args[0])+1 : len(args[0])+len(args[1])+len(args[2])+2]
	}
	return nil

View on GitHub (pinned to 3a66a489d2)

Solutions

1. Verify the header size token is a plain decimal byte count
2. Check for route protocol version mismatch between peers
3. Ensure nothing altered the message between sender and receiver

When it happens

Trigger: Thrown at server/route.go:262 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of nats-io/nats-server@3a66a489d2 (2026-09-02). Data as JSON: /api/errors/d6f8d9c621c8e66e. Report an issue: GitHub.