What causes "first event from binlog %v is not valid" in vitessio/vitess?

Verify the named file's integrity on the primary with mysqlbinlog; if truncated, stop serving it (or restore from backup).

vitessio/vitess · error

first event from binlog %v is not valid

Error message

first event from binlog %v is not valid

What it means

After sending ComBinlogDump for a candidate file, getBinlogTimeStamp validates that the very first event returned is a valid binlog event (event.IsValid()). If it is not, the file's stream cannot be trusted to find a timestamp, and this error naming the file is returned. This usually indicates the file is truncated, not a real binlog, or the server sent something unexpected.

Source

Thrown at go/vt/binlog/binlog_connection.go:282

	if err != nil {
		return 0, err
	}
	defer conn.Close()

	if err := conn.WriteComBinlogDump(bc.serverID, filename, 4, 0); err != nil {
		return 0, fmt.Errorf("failed to send the ComBinlogDump command: %v", err)
	}

	// Get the first event to get its timestamp. We skip
	// events that don't have timestamps (although it seems
	// most do anyway).
	for {
		event, err := conn.ReadBinlogEvent()
		if err != nil {
			return 0, fmt.Errorf("error reading binlog event %v: %v", filename, err)
		}
		if !event.IsValid() {
			return 0, fmt.Errorf("first event from binlog %v is not valid", filename)
		}
		if ts := event.Timestamp(); ts > 0 {
			return int64(ts), nil
		}
	}
}

// Close closes the binlog connection, which also signals an ongoing dump
// started with StartBinlogDump() to stop and close its BinlogEvent channel.
// The ID for the binlog connection is recycled back into the pool.
func (bc *BinlogConnection) Close() {
	if bc.Conn != nil {
		log.Info("closing binlog socket to unblock reads")
		bc.Conn.Close()

		// bc.cancel is set at the beginning of the StartBinlogDump*
		// methods. If we error out before then, it's nil.
		// Note we also may error out before adding 1 to bc.wg,

View on GitHub (pinned to 01a25a7d17)

Solutions

Verify the named file's integrity on the primary with mysqlbinlog; if truncated, stop serving it (or restore from backup).
Ensure the Vitess binary and MySQL server versions are compatible for replication protocol parsing.
Let findFileBeforeTimestamp proceed to an older intact binlog file if the requested timestamp allows it.
Check binlog_expire_logs_seconds / PURGE BINARY LOGS activity so files are not being removed or truncated during the scan.

Defensive patterns

Strategy: fallback

Validate before calling

// verify file integrity before probing
// mysqlbinlog binlog.000123 > /dev/null && echo OK || echo CORRUPT

Try / catch

if err != nil && strings.Contains(err.Error(), "is not valid") {
	// fall back to the next older binlog file, or re-seed from a backup
}

Prevention

Enable binlog checksums and verify files after any crash recovery.
Don't truncate or partially copy binlogs during storage moves.
Watch binlog expiration so files aren't purged mid-scan.
Keep replica Vitess/MySQL versions in supported combinations.

When it happens

Trigger: getBinlogTimeStamp reads a first event that fails IsValid() — typically a zero-length/garbage first packet from a truncated or partially purged binlog file, or a server-side error delivered as a non-event packet.

Common situations: Binlog files truncated by a primary crash; manual copying/rsyncing of binlogs producing incomplete files; version-mismatched replica reading binlogs written by an incompatible server; relay-style proxies injecting unexpected frames.

Related errors

AI-assisted analysis of vitessio/vitess@01a25a7d17 (2026-09-01). Data as JSON: /api/errors/c2d1c1822e345ee7. Report an issue: GitHub.