attempted to encode a malformed backend state file; data is…

Error message

attempted to encode a malformed backend state file; data is empty

What it means

StateStoreConfigState.Validate() returned immediately because the receiver is empty (nil or Type==""). Validate is called during EncodeBackendStateFile's state_store branch, so the message uses the backend-state framing: the file is being encoded with a non-nil StateStore pointer whose content is empty.

Solutions

If writing tooling, always populate Type (and other required fields) before encoding, or leave StateStore nil.
In normal use, delete the malformed file and `terraform init` to rebuild it.
Audit the code path that allocates StateStoreConfigState — it should fully populate or remain nil.

Example fix

// before
f := &BackendStateFile{StateStore: &StateStoreConfigState{}}
EncodeBackendStateFile(f) // -> data is empty

// after — populate or omit
f.StateStore = nil
// or
f.StateStore = &StateStoreConfigState{Type: "kubernetes", Provider: ..., ConfigRaw: ...}

Defensive patterns

Strategy: validation

Validate before calling

// pre-flight: skip encode when there's nothing to encode
if s != nil && s.Empty() {
    return errors.New("StateStoreConfigState is empty; set fields or leave StateStore nil")
}

Type guard

func (s *StateStoreConfigState) isPopulated() bool {
    return s != nil && s.Type != "" && s.Provider != nil && s.ConfigRaw != nil
}

Prevention

When building BackendStateFile in code, either fully populate StateStore or leave it nil.
Add a constructor that enforces required fields.

When it happens

Trigger: Code constructs a BackendStateFile with StateStore != nil but the StateStoreConfigState has no Type set (or is the zero value). Indicates an internal construction bug rather than user config.

Common situations: Custom tooling that builds a BackendStateFile programmatically without populating StateStore fields; a partially-initialised state object after a failed migration.

Understand the failure class

Parsing and encoding errors: unexpected token, malformed input — why parsers reject input and how to find the real culprit.

Related errors

AI-assisted analysis of hashicorp/terraform@d32a084675 (2026-08-11). Data as JSON: /api/errors/ff66b45713330195. Report an issue: GitHub.

Appendix: source

Thrown at internal/command/workdir/statestore_config_state.go:46

	Type               string                          `json:"type"`                 // State store type name
	Provider           *ProviderConfigState            `json:"provider"`             // Details about the state-storage provider
	ConfigRaw          json.RawMessage                 `json:"config"`               // state_store block raw config, barring provider details
	Hash               uint64                          `json:"hash"`                 // Hash of the state_store block's configuration, including the nested provider block
	ProviderSupplyMode getproviders.ProviderSupplyMode `json:"provider_supply_mode"` // How the provider was supplied to Terraform during the init operation that created this config state.
}

// Empty returns true if there is no active state store.
func (s *StateStoreConfigState) Empty() bool {
	return s == nil || s.Type == ""
}

// Validate returns true if there are no missing expected values, and
// important values have been validated, e.g. FQNs. When the config is
// invalid an error will be returned.
func (s *StateStoreConfigState) Validate() error {
	// Are any bits of data totally missing?
	if s.Empty() {
		return fmt.Errorf("attempted to encode a malformed backend state file; data is empty")
	}
	if s.Type == "" {
		return fmt.Errorf("attempted to encode a malformed backend state file; state store type is missing")
	}
	if s.Provider == nil {
		return fmt.Errorf("attempted to encode a malformed backend state file; provider data is missing")
	}
	if s.ConfigRaw == nil {
		return fmt.Errorf("attempted to encode a malformed backend state file; state_store configuration data is missing")
	}

	// Validity of data that is there
	err := s.Provider.Source.Validate()
	if err != nil {
		return fmt.Errorf("state store is not valid: %w", err)
	}

	// Version information is required if the provider isn't builtin or unmanaged by Terraform

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