gohugoio/hugo · error

failed to compile Redirect regexp %q: %w

Error message

failed to compile Redirect regexp %q: %w

What it means

Raised by Server.CompileConfig when the `fromRe` field of a `[[server.redirects]]` entry fails regexp.Compile. `fromRe` is a Go RE2 regular expression matched against request paths (supporting capture-group substitution in `to`), and an invalid pattern aborts config loading.

Source

Thrown at config/commonConfig.go:277

	}
	for _, r := range s.Redirects {
		if r.From == "" && r.FromRe == "" {
			return fmt.Errorf("redirects must have either From or FromRe set")
		}
		rd := redirect{
			headers: make(map[string]glob.Glob),
		}
		if r.From != "" {
			g, err := glob.Compile(r.From)
			if err != nil {
				return fmt.Errorf("failed to compile Redirect glob %q: %w", r.From, err)
			}
			rd.from = g
		}
		if r.FromRe != "" {
			re, err := regexp.Compile(r.FromRe)
			if err != nil {
				return fmt.Errorf("failed to compile Redirect regexp %q: %w", r.FromRe, err)
			}
			rd.fromRe = re
		}
		for k, v := range r.FromHeaders {
			g, err := glob.Compile(v)
			if err != nil {
				return fmt.Errorf("failed to compile Redirect header glob %q: %w", v, err)
			}
			rd.headers[k] = g
		}
		s.compiledRedirects = append(s.compiledRedirects, rd)
	}

	return nil
}

func (s *Server) MatchHeaders(pattern string) []types.KeyValueStr {
	if s.compiledHeaders == nil {

View on GitHub ↗ (pinned to 8a468df065)

Solutions

1. Fix the regexp quoted in the error to valid Go RE2 syntax; remove lookarounds and backreferences.
2. In TOML, use single-quoted literal strings (`fromRe = '^/post/(\d+)$'`) to avoid backslash-escaping mistakes.
3. If you only need wildcard matching, use the `from` glob field instead of `fromRe`.

Example fix

# before (hugo.toml)
[[server.redirects]]
fromRe = "^/post/(\\d+"
to = "/blog/$1"

# after
[[server.redirects]]
fromRe = '^/post/(\d+)$'
to = "/blog/$1"

if r.FromRe != "" {
    if _, err := regexp.Compile(r.FromRe); err != nil {
        return fmt.Errorf("redirect 'fromRe' %q invalid: %w", r.FromRe, err)
    }
}

if err := cfg.Server.CompileConfig(logger); err != nil {
    // "failed to compile Redirect regexp" — validate the fromRe with Go's RE2 syntax
    return err
}

When it happens

Trigger: A `[[server.redirects]]` entry with `fromRe` containing invalid RE2 syntax — e.g. `fromRe = "^/blog/(\\d+"` (unclosed group), PCRE lookarounds like `(?<!x)` / `(?=x)`, or backreferences `\\1`, none of which Go's regexp package supports.

Common situations: Porting nginx/Apache rewrite regexps that use lookahead or backreferences; forgetting to double-escape backslashes in TOML basic strings; putting glob syntax like `**` in `fromRe` where it means something different in a regexp.

Related errors

• redirects must have either From or FromRe set
• failed to compile Redirect glob %q: %w
• failed to compile Redirect header glob %q: %w
• failed to compile cache buster %q: %w
• failed to compile Headers glob %q: %w

AI-assisted analysis of gohugoio/hugo@8a468df065 (2026-07-31). Data as JSON: /data/errors/12f45b0e3a35dec2.json. Report an issue: GitHub ↗.