prometheus/node_exporter · error

invalid TCP states data: expected

Error message

invalid TCP states data: expected %d entries, found %d

What it means

The FreeBSD netstat collector reads the kernel TCP state table via sysctl and expects the returned binary buffer to contain exactly one 8-byte entry per known TCP state. If the buffer size divided by 8 does not match the length of the tcpStates name table, the collector cannot safely map entries to state names and returns this error instead of emitting wrong metrics.

Solutions

1. Rebuild/run the node_exporter version that matches your FreeBSD kernel version so the tcpStates table matches the kernel's output.
2. Verify the sysctl value backing this data (e.g. net.inet.tcp.states / kern IPC data) returns the expected entry count on the host.
3. If a kernel version changed the state list, update the tcpStates table in collector/netstat_freebsd.go to match and file/track an upstream issue.
4. Report the kernel version and the 'found' value from the error message upstream to help extend the compatibility table.

Example fix

// before (collector assumes fixed state count)
if len(data)/8 != len(tcpStates) {
	return nil, fmt.Errorf("invalid TCP states data: expected %d entries, found %d", len(tcpStates), len(data)/8)
}
// after (optionally tolerate extra kernel entries by parsing only the known prefix)
if len(data)/8 < len(tcpStates) {
	return nil, fmt.Errorf("invalid TCP states data: expected at least %d entries, found %d", len(tcpStates), len(data)/8)
}

// Before parsing, check that the sysctl buffer size matches the state table
// (this is what the collector does; if you extend it, keep the check):
// data, _ := sysctlRaw(...)
// if len(data)/8 != len(tcpStates) { /* skip TCP state metrics this scrape */ }

null

null

When it happens

Trigger: The sysctl call returns a buffer whose length/8 differs from len(tcpStates); this happens when the kernel returns fewer or more TCP state counters than the collector's hardcoded state list (e.g. a newer/older FreeBSD kernel with a changed number of TCP states, or a truncated/partial sysctl read).

Common situations: Running node_exporter built for one FreeBSD version on a kernel with a different TCPstate count; unusual kernels or ABI drift between userland sysctl expectations and the running kernel.

Understand the failure class

Background: Schema validation failed / invalid input schema: payload rejected because its shape doesn't match the expected schema — this error's family across 28 libraries.

Related errors

• Data Size mismatch
• sysctl(vm.stats.vm.v_page_size) failed
• couldn't get memory
• couldn't get sysctl
• could not retrieve CPU times

AI-assisted analysis of prometheus/node_exporter@17ddd77c59 (2026-09-07). Data as JSON: /api/errors/e7d04d5038a9fab0. Report an issue: GitHub.

Appendix: source

Thrown at collector/netstat_freebsd.go:265

	}

	if len(data) < expectedSize {
		return nil, errors.New("Data Size mismatch")
	}
	return data, nil
}

func getTCPStates() ([]uint64, error) {

	// This sysctl returns an array of uint64
	data, err := sysctlRaw("net.inet.tcp.states")

	if err != nil {
		return nil, err
	}

	if len(data)/8 != len(tcpStates) {
		return nil, fmt.Errorf("invalid TCP states data: expected %d entries, found %d", len(tcpStates), len(data)/8)
	}

	states := make([]uint64, 0)

	offset := 0
	for range len(tcpStates) {
		s := data[offset : offset+8]
		offset += 8
		states = append(states, binary.NativeEndian.Uint64(s))
	}
	return states, nil
}

type netStatCollector struct {
	netStatMetric *prometheus.Desc
}

func init() {

View on GitHub (pinned to 17ddd77c59)