hashicorp/terraform · error

Failed to marshal state to json: %s

Error message

Failed to marshal state to json: %s

What it means

Thrown by `terraform state show` when jsonstate.MarshalForRenderer(mockFile, schemas) fails while converting the single resource instance into the JSON renderer representation. MarshalForRenderer encodes the state plus provider schemas; failure indicates the resource instance or its provider schema could not be serialized — typically a schema/type mismatch or an internal encoding error. The %s is the underlying marshal error.

Source

Thrown at internal/command/state_show.go:151

	// check if the resource has a configured provider, otherwise this will use the default provider
	rs := state.Resource(addr.ContainingResource())
	absPc := addrs.AbsProviderConfig{
		Provider: rs.ProviderConfig.Provider,
		Alias:    rs.ProviderConfig.Alias,
		Module:   addrs.RootModule,
	}
	singleInstance := states.NewState()
	singleInstance.EnsureModule(addr.Module).SetResourceInstanceCurrent(
		addr.Resource,
		is.Current,
		absPc,
	)

	mockFile := statefile.New(singleInstance, "", 0)
	root, outputs, err := jsonstate.MarshalForRenderer(mockFile, schemas)
	if err != nil {
		diags = diags.Append(fmt.Errorf("Failed to marshal state to json: %s", err))
		return view.DisplayResourceInstanceState(jsonformat.State{}, diags)
	}

	jstate := jsonformat.State{
		StateFormatVersion:    jsonstate.FormatVersion,
		ProviderFormatVersion: jsonprovider.FormatVersion,
		RootModule:            root,
		RootModuleOutputs:     outputs,
		ProviderSchemas:       jsonprovider.MarshalForRenderer(schemas),
	}

	return view.DisplayResourceInstanceState(jstate, diags)
}

func (c *StateShowCommand) Help() string {
	helpText := `
Usage: terraform [global options] state show [options] ADDRESS

View on GitHub (pinned to c9def3e214)

Solutions

1. Read the %s for the attribute/type that failed to marshal.
2. Run `terraform refresh` (or `terraform apply -refresh-only`) to reconcile state with the current provider schema, then retry state show.
3. If a provider downgrade caused it, restore the provider version that wrote the state via required_providers.
4. As a last resort, taint/remove the offending resource and re-apply.

Example fix

# before
aws_instance.web state written by provider v3; now using v5
terraform state show aws_instance.web
# Failed to marshal state to json: ...

# after
terraform apply -refresh-only
terraform state show aws_instance.web

// validate a resource instance's state shape against provider schema
// before marshalling (conceptual)
func instanceMatchesSchema(is *states.ResourceInstance, schema *configschema.Block) error {
    // decode instance state via schema.ImpliedType and surface mismatch
    return nil
}

When it happens

Trigger: Running `terraform state show <addr>` for a resource instance whose state shape does not match its provider's current schema, so marshalling the filtered state to JSON fails. Often seen after a provider schema change without refresh, or with a corrupt/inconsistent state value.

Common situations: Provider upgraded with breaking schema change; resource in state written by a much older provider; state manually edited; cty value/type drift between state and schema; resource type renamed.

Related errors

• credentials file %s has invalid value for "credentials" prop
• Can't serialize backend configuration as JSON: %s
• Failed to set state store configuration: %w
• Failed to set state store provider configuration: %w
• Can't serialize backend configuration as JSON: %s

AI-assisted analysis of hashicorp/terraform@c9def3e214 (2026-08-07). Data as JSON: /api/errors/b81cc8f29bb1fd2b. Report an issue: GitHub.