# Common Errors
<a name="CommonErrors"></a>

This section lists the common errors that all actions return. Any action-specific errors are listed in the topic for the action.

 **IncompleteSignature**   
The request signature does not conform to AWS standards.  
HTTP Status Code: 400

 **InternalFailure**   
The request processing has failed because of an unknown error, exception or failure.  
HTTP Status Code: 500

 **InvalidAction**   
The action or operation requested is invalid. Verify that the action is typed correctly.  
HTTP Status Code: 400

 **InvalidClientTokenId**   
The X.509 certificate or AWS access key ID provided does not exist in our records.  
HTTP Status Code: 403

 **InvalidParameterCombination**   
Parameters that must not be used together were used together.  
HTTP Status Code: 400

 **InvalidParameterValue**   
An invalid or out-of-range value was supplied for the input parameter.  
HTTP Status Code: 400

 **InvalidQueryParameter**   
The AWS query string is malformed or does not adhere to AWS standards.  
HTTP Status Code: 400

 **MalformedQueryString**   
The query string contains a syntax error.  
HTTP Status Code: 404

 **MissingAction**   
The request is missing an action or a required parameter.  
HTTP Status Code: 400

 **MissingAuthenticationToken**   
The request must contain either a valid (registered) AWS access key ID or X.509 certificate.  
HTTP Status Code: 403

 **MissingParameter**   
A required parameter for the specified action is not supplied.  
HTTP Status Code: 400

 **OptInRequired**   
The AWS access key ID needs a subscription for the service.  
HTTP Status Code: 403

 **RequestExpired**   
The request reached the service more than 15 minutes after the date stamp on the request or more than 15 minutes after the request expiration date (such as for pre-signed URLs), or the date stamp on the request is more than 15 minutes in the future.  
HTTP Status Code: 400

 **ServiceUnavailable**   
The request has failed due to a temporary failure of the server.  
HTTP Status Code: 503

 **Throttling**   
The request was denied due to request throttling.  
HTTP Status Code: 400

 **ValidationError**   
The input fails to satisfy the constraints specified by an AWS service.  
HTTP Status Code: 400