Numeric PreRelease version must not contain leading zeroes %

Error message

Numeric PreRelease version must not contain leading zeroes %q

What it means

Semver parse error from NewPRVersion(): a prerelease identifier that is entirely numeric contains a leading zero (e.g. pre-release "01" in 1.2.3-01). Numeric prerelease identifiers must not have leading zeros under SEMVER 2.0.0 (alphanumeric ones like 'alpha01' are fine).

Source

Thrown at src/semver/semver.go:301

	return v, nil
}

// PreRelease Version
type PRVersion struct {
	VersionStr string
	VersionNum uint64
	IsNum      bool
}

// Creates a new valid prerelease version
func NewPRVersion(s string) (*PRVersion, error) {
	if len(s) == 0 {
		return nil, errors.New("Prerelease is empty")
	}
	v := &PRVersion{}
	if containsOnly(s, numbers) {
		if hasLeadingZeroes(s) {
			return nil, fmt.Errorf("Numeric PreRelease version must not contain leading zeroes %q", s)
		}
		num, err := strconv.ParseUint(s, 10, 64)

		// Might never be hit, but just in case
		if err != nil {
			return nil, err
		}
		v.VersionNum = num
		v.IsNum = true
	} else if containsOnly(s, alphanum) {
		v.VersionStr = s
		v.IsNum = false
	} else {
		return nil, fmt.Errorf("Invalid character(s) found in prerelease %q", s)
	}
	return v, nil
}

View on GitHub (pinned to 5b18223ca1)

Solutions

Remove leading zeroes from numeric prerelease identifiers: 1.2.3-01 -> 1.2.3-1
Make the identifier alphanumeric if padding must be preserved: 1.2.3-build02
Fix the release script that emits padded numeric identifiers

Example fix

// before
v, err := semver.NewVersion("1.2.3-rc.01")

// after
v, err := semver.NewVersion("1.2.3-rc.1")

Defensive patterns

Strategy: validation

Validate before calling

var numericIdent = regexp.MustCompile(`^(0|[1-9]\d*)$`)
func validPrerelease(pre string) bool {
    for _, id := range strings.Split(pre, ".") {
        if isAllDigits(id) && !numericIdent.MatchString(id) { return false }
    }
    return true
}

Prevention

Format prerelease counters without padding (%d, never %02d)
Keep padded identifiers alphanumeric (build02, not 02) to sidestep the rule
Unit-test version parsing against the full semver.org spec corpus

When it happens

Trigger: semver.NewVersion("1.2.3-01"), "1.2.3-rc.007", or any dash-separated prerelease part where a dot-delimited identifier is all digits and starts with '0' but is not '0' itself.

Common situations: Zero-padded prerelease counters from build pipelines (1.0.0-beta.02), calendar-padded nightly identifiers, or hand-written versions copied from padded changelogs.

Related errors

AI-assisted analysis of coreybutler/nvm-windows@5b18223ca1 (2026-08-15). Data as JSON: /api/errors/3b2bc42a29a96db5. Report an issue: GitHub.