# Resource type handler error codes
<a name="resource-type-test-contract-errors"></a>

One of the following error codes MUST be returned from the handler whenever there is a [progress event](https://docs.aws.amazon.com/cloudformation-cli/latest/userguide/resource-type-test-progressevent.html) with an operation status of `FAILED`.
+ `AccessDenied`

  The customer has insufficient permissions to perform this request.

  *Type:* Terminal
+ `AlreadyExists`

  The specified resource already existed before the execution of this handler. This error is applicable to `create` handlers only.

  *Type:* Terminal
+ `GeneralServiceException`

  The downstream service generated an error that doesn't map to any other handler error code.

  *Type:* Terminal
+ `InternalFailure`

  An unexpected error occurred within the handler.

  *Type:* Terminal
+ `InvalidCredentials`

  The credentials provided by the user are invalid.

  *Type:* Terminal
+ `InvalidRequest`

  Invalid input from the user has generated a generic exception.

  *Type:* Terminal
+ `NetworkFailure`

  The request couldn't be completed due to networking issues, such as a failure to receive a response from the server.

  *Type:* Retriable
+ `NotFound`

  The specified resource doesn't exist, or is in a terminal, inoperable, and irrecoverable state.

  *Type:* Terminal
+ `NotStabilized`

  The downstream resource failed to complete all of its ready-state checks.

  *Type:* Terminal
+ `NotUpdatable`

  The user has requested an update to a property defined in the resource type schema as a [create-only property](https://docs.aws.amazon.com/cloudformation-cli/latest/userguide/resource-type-schema.html#schema-properties-createonlyproperties). This error is applicable to `update` handlers only.

  *Type:* Terminal
+ `ResourceConflict`

  The resource is temporarily unavailable to be acted upon. For example, if the resource is currently undergoing an operation and can't be acted upon until that operation is finished.

  *Type:* Retriable
+ `ServiceInternalError`

  The downstream service returned an internal error, typically with a `5XX` HTTP Status code.

  *Type:* Retriable
+ `ServiceLimitExceeded`

  A non-transient resource limit was reached on the service side.

  *Type:* Terminal
+ `Throttling`

  The request was throttled by a downstream service.

  *Type:* Retriable