caddyserver/caddy · error

missing or empty key on line %d

Error message

missing or empty key on line %d

What it means

parseEnvFile rejects a line whose key is empty after splitting on '=' and stripping an optional `export ` prefix. That means the line starts with '=' (value with no key), or is exactly `export` with nothing after it.

Source

Thrown at cmd/main.go:412

		// skip empty lines and lines starting with comment
		if line == "" || strings.HasPrefix(line, "#") {
			continue
		}

		// split line into key and value
		before, after, isCut := strings.Cut(line, "=")
		if !isCut {
			return nil, fmt.Errorf("can't parse line %d; line should be in KEY=VALUE format", lineNumber)
		}
		key, val := before, after

		// sometimes keys are prefixed by "export " so file can be sourced in bash; ignore it here
		key = strings.TrimPrefix(key, "export ")

		// validate key and value
		if key == "" {
			return nil, fmt.Errorf("missing or empty key on line %d", lineNumber)
		}
		if strings.Contains(key, " ") {
			return nil, fmt.Errorf("invalid key on line %d: contains whitespace: %s", lineNumber, key)
		}
		if strings.HasPrefix(val, " ") || strings.HasPrefix(val, "\t") {
			return nil, fmt.Errorf("invalid value on line %d: whitespace before value: '%s'", lineNumber, val)
		}

		// remove any trailing comment after value
		if commentStart, _, found := strings.Cut(val, "#"); found {
			val = strings.TrimRight(commentStart, " \t")
		}

		// quoted value: support newlines
		if strings.HasPrefix(val, `"`) || strings.HasPrefix(val, "'") {
			quote := string(val[0])
			for !strings.HasSuffix(line, quote) || strings.HasSuffix(line, `\`+quote) {
				val = strings.ReplaceAll(val, `\`+quote, quote)

View on GitHub (pinned to 50e54ee279)

Solutions

1. Inspect the reported line and restore the missing key name before the '='
2. Delete stray `=` or `=`+value lines
3. If the line came from a template, fix the template variable so it renders an actual key

Example fix

# before (line 2)
=DEBUG

# after
LOG_LEVEL=DEBUG

grep -nE '^(export )?=' env && echo 'empty key line(s) found' || echo OK

When it happens

Trigger: A line like `=value`, `=` alone, or `export ` followed by `=something` with the variable name missing (e.g. a failed sed/edit leaving `export =foo`).

Common situations: Template substitution that produced an empty variable name (`${}=value`), hand-editing accidents, or find-replace that deleted the key but left the '=' and value.

Related errors

• parsing environment file: %v
• can't parse line %d; line should be in KEY=VALUE format
• invalid key on line %d: contains whitespace: %s
• invalid value on line %d: whitespace before value: '%s'
• unmarshaling admin listener address from config: %v

AI-assisted analysis of caddyserver/caddy@50e54ee279 (2026-08-15). Data as JSON: /api/errors/516974a9e9c3a0a4. Report an issue: GitHub.