nektos/act · error

invalid format '%v', expected a line with '=' or '<<'

Error message

invalid format '%v', expected a line with '=' or '<<'

What it means

Thrown by the .env file parser when a line contains neither '=' (key=value) nor act's heredoc marker '<<'. Every non-comment line in an env file must be KEY=VALUE or KEY<<DELIM; anything else is rejected.

Source

Thrown at pkg/container/parse_env_file.go:63

				multiLineEnvDelimiter := line[multiLineEnv+2:]
				delimiterFound := false
				for s.Scan() {
					content := s.Text()
					if content == multiLineEnvDelimiter {
						delimiterFound = true
						break
					}
					if multiLineEnvContent != "" {
						multiLineEnvContent += "\n"
					}
					multiLineEnvContent += content
				}
				if !delimiterFound {
					return fmt.Errorf("invalid format delimiter '%v' not found before end of file", multiLineEnvDelimiter)
				}
				localEnv[line[:multiLineEnv]] = multiLineEnvContent
			} else {
				return fmt.Errorf("invalid format '%v', expected a line with '=' or '<<'", line)
			}
		}
		env = &localEnv
		return s.Err()
	}
}

View on GitHub (pinned to 4f41128141)

Solutions

1. Convert 'export KEY=value' lines to plain 'KEY=value'.
2. Remove shell syntax (set, comments without #, blank commands) from the env file.
3. Prefix comment lines with # so the parser skips them.
4. Run a quick lint: awk -F= 'NF<2 && $0!~/^#/' file to find offending lines.

Example fix

# before (.env)
export DEBUG=1
set -e
# after (.env)
DEBUG=1

func lintEnvFile(path string) error {
  f, _ := os.Open(path)
  defer f.Close()
  s := bufio.NewScanner(f)
  for s.Scan() {
    l := s.Text()
    if l == '' || strings.HasPrefix(l, '#') { continue }
    if !strings.Contains(l, '=') && !strings.Contains(l, '<<') {
      return fmt.Errorf('malformed env line: %q', l)
    }
  }
  return nil
}

When it happens

Trigger: Passing --env-file a shell script (with export statements, quotes only, or bare words); stray lines like 'set -e', continuation lines, or prose in the env file.

Common situations: Reusing a shell env script as act env file; files with BOM or Windows artifacts; typo like 'KEY =value' handled elsewhere but a truly malformed line 'KEY value' hits this.

Related errors

• invalid format delimiter '%v' not found before end of file
• --pid: invalid PID mode
• --cgroupns: invalid CGROUP mode
• network-scoped aliases are only supported for user-defined n
• links are only supported for user-defined networks

AI-assisted analysis of nektos/act@4f41128141 (2026-08-15). Data as JSON: /api/errors/d8abaed65f432880. Report an issue: GitHub.