attempted to encode a malformed backend state file; state…

Error message

attempted to encode a malformed backend state file; state store type is missing

What it means

StateStoreConfigState.Validate() found Empty() == false (Type was previously something?) Actually the order is: Empty() check passes (so s != nil and Type != "" would normally hold), but the next guard checks Type == "" again. In practice this branch is unreachable given Empty()'s definition (Empty returns true when Type==""). Hitting it means Type was mutated between checks, or a logic bug.

Solutions

Treat as a bug: report it with a reproduction case.
Ensure StateStoreConfigState is not shared across goroutines; copy before encoding.
Populate Type explicitly when constructing the struct.

Example fix

// ensure Type is set before Validate()
if s.Type == "" { s.Type = "kubernetes" }

Defensive patterns

Strategy: validation

Validate before calling

// pre-flight: combine the two checks into one to avoid races
if s == nil || s.Type == "" {
    return errors.New("state store type is missing")
}

Prevention

Don't share StateStoreConfigState across goroutines without synchronisation.
Prefer value semantics: copy before passing to encoder.

When it happens

Trigger: Concurrent mutation of the StateStoreConfigState between the Empty() and Type=="" checks, or a fork that changed Empty()'s definition. Effectively unreachable in stock Terraform.

Common situations: Race condition on the struct, custom fork, or reflective tampering. Should never occur in normal single-threaded init/plan/apply.

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/796c32a50015a248. Report an issue: GitHub.

Appendix: source

Thrown at internal/command/workdir/statestore_config_state.go:49

	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
	switch s.ProviderSupplyMode {
	case getproviders.BuiltIn, getproviders.Reattached, getproviders.DevOverride:
		// These modes do not require version information

View on GitHub (pinned to d32a084675)