oauth2-proxy/oauth2-proxy · error

error unmarshalling config: %w

Error message

error unmarshalling config: %w

What it means

Wrap error in options.Load: viper's UnmarshalExact failed while mapping config file/flags onto the options struct. Because ErrorUnused is in effect, this commonly means the config contains a key that does not map to any option, or a value has the wrong type for its field.

Source

Thrown at pkg/apis/options/load.go:52

	if configFileName != "" {
		err := v.ReadInConfig()
		if err != nil {
			return fmt.Errorf("unable to load config file: %w", err)
		}
	}

	err := registerFlags(v, "", flagSet, into)
	if err != nil {
		// This should only happen if there is a programming error
		return fmt.Errorf("unable to register flags: %w", err)
	}

	// UnmarshalExact will return an error if the config includes options that are
	// not mapped to fields of the into struct
	err = v.UnmarshalExact(into, decodeFromCfgTag)
	if err != nil {
		return fmt.Errorf("error unmarshalling config: %w", err)
	}

	return nil
}

// LoadYAML will load a YAML based configuration file into the options interface provided.
func LoadYAML(configFileName string, opts interface{}) error {
	buffer, err := loadAndSubstituteEnvs(configFileName)
	if err != nil {
		return err
	}

	// Generic interface for loading arbitrary yaml structure
	var intermediate map[string]interface{}

	if err := yaml.Unmarshal(buffer, &intermediate); err != nil {
		return fmt.Errorf("error unmarshalling config: %w", err)
	}

View on GitHub (pinned to 33c2eb92de)

Solutions

1. Find the offending key in the error detail and correct or remove it
2. Check spelling and nesting of the option in the config file
3. Ensure values match the expected types (strings, durations, byte sizes)

When it happens

Trigger: Thrown at pkg/apis/options/load.go:52 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of oauth2-proxy/oauth2-proxy@33c2eb92de (2026-09-06). Data as JSON: /api/errors/72e0d0c426776cb7. Report an issue: GitHub.