What causes "redirect match: status code digits: %s: %v" in kataras/iris?

Shorten the code field to a valid HTTP status code (100–599).

redirect match: status code digits: %s: %v

Error message

redirect match: status code digits: %s: %v

What it means

After confirming the code field is all digits, parseRedirectMatchLine still calls strconv.Atoi as a defensive second check. If Atoi fails (e.g. the digits overflow int), the parse fails with this error wrapping the strconv error. It is the fallback arm of the digit validation and rarely fires because the digit loop already ran.

Source

Thrown at middleware/rewrite/rewrite.go:299

func parseRedirectMatchLine(s string) (*redirectMatch, error) {
	parts := strings.Split(strings.TrimSpace(s), " ")
	if len(parts) != 3 {
		return nil, fmt.Errorf("redirect match: invalid line: %s", s)
	}

	codeStr, pattern, target := parts[0], parts[1], parts[2]

	for i, ch := range codeStr {
		if !isDigit(ch) {
			return nil, fmt.Errorf("redirect match: status code digits: %s [%d:%c]", codeStr, i, ch)
		}
	}

	code, err := strconv.Atoi(codeStr)
	if err != nil {
		// this should not happen, we check abt digit
		// and correctly position the error too but handle it.
		return nil, fmt.Errorf("redirect match: status code digits: %s: %v", codeStr, err)
	}

	regex := regexp.MustCompile(pattern)
	if regex.MatchString(target) {
		return nil, fmt.Errorf("redirect match: loop detected: pattern: %s vs target: %s", pattern, target)
	}

	v := &redirectMatch{
		code:              code,
		pattern:           regex,
		target:            target,
		noRedirect:        code <= 0,
		isRelativePattern: pattern[0] == '/', // search by path.
	}

	return v, nil
}

View on GitHub (pinned to 7bedaf55a0)

Solutions

Shorten the code field to a valid HTTP status code (100–599).
Ensure the code field is the actual status code, not a timestamp or ID accidentally placed first.
Keep the line format strictly 'CODE PATTERN TARGET' so digits land in the right slot.

Example fix

// before
rewrite.New([]rewrite.RedirectMatchLine{"99999999999999999999 /old /new"})
// after
rewrite.New([]rewrite.RedirectMatchLine{"302 /old /new"})

Defensive patterns

Strategy: validation

Validate before calling

code, err := strconv.Atoi(strings.Fields(line)[0])
if err != nil || code < 100 || code > 599 {
    return fmt.Errorf("invalid status code in redirect line %q", line)
}

Try / catch

if _, err := rewrite.New(lines); err != nil {
    log.Fatalf("redirect line rejected: %v", err) // includes strconv detail
}

Prevention

Restrict code fields to real HTTP status codes (100–599).
Never paste long numeric IDs into the code position.
Validate configs with strconv.Atoi in a pre-flight test.

When it happens

Trigger: A redirect line whose code field is all digits but not convertible by strconv.Atoi — practically only a numeric string exceeding platform int range (e.g. '99999999999999999999 /old /new').

Common situations: Pasting a very long numeric field into the code position, or machine-generated configs with corrupted numeric fields.

Related errors

AI-assisted analysis of kataras/iris@7bedaf55a0 (2026-08-30). Data as JSON: /api/errors/3119e39bb0f1c673. Report an issue: GitHub.