What causes "cannot parse timestamp milliseconds from %q: %w" in VictoriaMetrics/VictoriaMetrics?

Fix the offending cell to a plain integer of milliseconds

cannot parse timestamp milliseconds from %q: %w

Error message

cannot parse timestamp milliseconds from %q: %w

What it means

Raised in parseUnixTimestampMilliseconds (csvimport time format unix_ms) when fastfloat.ParseInt64 cannot parse the cell as an integer millisecond timestamp. The wrapped error explains the parse failure for the given cell value %q.

Source

Thrown at lib/protoparser/csvimport/column_descriptor.go:156

		return nil, fmt.Errorf("unknown format for time parsing: %q; supported formats: unix_s, unix_ms, unix_ns, rfc3339", format)
	}
}

func parseUnixTimestampSeconds(s string) (int64, error) {
	n, err := fastfloat.ParseInt64(s)
	if err != nil {
		return 0, fmt.Errorf("cannot parse timestamp seconds from %q: %w", s, err)
	}
	if n > int64(1<<63-1)/1e3 {
		return 0, fmt.Errorf("too big unix timestamp in seconds: %d; must be smaller than %d", n, int64(1<<63-1)/1e3)
	}
	return n * 1e3, nil
}

func parseUnixTimestampMilliseconds(s string) (int64, error) {
	n, err := fastfloat.ParseInt64(s)
	if err != nil {
		return 0, fmt.Errorf("cannot parse timestamp milliseconds from %q: %w", s, err)
	}
	return n, nil
}

func parseUnixTimestampNanoseconds(s string) (int64, error) {
	n, err := fastfloat.ParseInt64(s)
	if err != nil {
		return 0, fmt.Errorf("cannot parse timestamp nanoseconds from %q: %w", s, err)
	}
	return n / 1e6, nil
}

func parseRFC3339(s string) (int64, error) {
	t, err := time.Parse(time.RFC3339, s)
	if err != nil {
		return 0, fmt.Errorf("cannot parse time in RFC3339 from %q: %w", s, err)
	}
	return t.UnixNano() / 1e6, nil

View on GitHub (pinned to 5079fb58f1)

Solutions

Fix the offending cell to a plain integer of milliseconds
Replace sentinel values like 'N/A', 'null', or empty cells with real timestamps or drop those rows
If data is a formatted date, switch the spec to time:rfc3339 or a custom format
Trim whitespace, quotes, and BOM from cells before import

Example fix

// before (CSV cell)
N/A
cds, _ := csvimport.ParseColumnDescriptors("time:unix_ms,metric")
// after
1700000000000

Defensive patterns

Strategy: try-catch

Validate before calling

func isUnixMillis(v string) bool {
	n, err := strconv.ParseInt(strings.TrimSpace(v), 10, 64)
	return err == nil && n >= 0
}

Try / catch

if err != nil && strings.Contains(err.Error(), "cannot parse timestamp milliseconds") {
	// log the offending cell from the quoted %q and skip/repair that row
}

Prevention

Trim and normalize cells before Unmarshal
Scan the time column once with strconv.ParseInt to find all bad rows up front
Keep timestamp columns free of locale formatting in the upstream exporter

When it happens

Trigger: A row's time column with spec time:unix_ms contains non-numeric text, an empty string, a float with a fractional part that fails strict int parsing, a formatted date, or a number with thousands separators.

Common situations: CSV cells from spreadsheet exports with date formatting; whitespace/BOM; data actually in seconds (which would parse but yield wrong times — this error instead indicates true non-numeric junk like 'N/A' or 'null').

Related errors

AI-assisted analysis of VictoriaMetrics/VictoriaMetrics@5079fb58f1 (2026-09-03). Data as JSON: /api/errors/39aed79f67be65b1. Report an issue: GitHub.