docker/cli · error

unexpected environment variable '%s'

Error message

unexpected environment variable '%s'

What it means

Error "unexpected environment variable '%s'" thrown in docker/cli.

Source

Thrown at cli/command/stack/loader.go:136

func buildEnvironment(env []string) (map[string]string, error) {
	result := make(map[string]string, len(env))
	for _, s := range env {
		if runtime.GOOS == "windows" && len(s) > 0 {
			// cmd.exe can have special environment variables which names start with "=".
			// They are only there for MS-DOS compatibility and we should ignore them.
			// See TestBuildEnvironment for examples.
			//
			// https://ss64.com/nt/syntax-variables.html
			// https://devblogs.microsoft.com/oldnewthing/20100506-00/?p=14133
			// https://github.com/docker/cli/issues/4078
			if s[0] == '=' {
				continue
			}
		}

		k, v, ok := strings.Cut(s, "=")
		if !ok || k == "" {
			return result, fmt.Errorf("unexpected environment variable '%s'", s)
		}
		// value may be set, but empty if "s" is like "K=", not "K".
		result[k] = v
	}
	return result, nil
}

func loadConfigFiles(filenames []string, stdin io.Reader) ([]composetypes.ConfigFile, error) {
	configFiles := make([]composetypes.ConfigFile, 0, len(filenames))

	for _, filename := range filenames {
		configFile, err := loadConfigFile(filename, stdin)
		if err != nil {
			return configFiles, err
		}
		configFiles = append(configFiles, *configFile)
	}

View on GitHub (pinned to e9452d6e78)

When it happens

Trigger: Thrown at cli/command/stack/loader.go:136 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of docker/cli@e9452d6e78 (2026-08-01). Data as JSON: /data/errors/7ac1bb3bf2d35252.json. Report an issue: GitHub.