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[SMS Global Knowledgebase](https://knowledgebase.smsglobal.com/?hsLang=en-au) 2. [API and Integration](https://knowledgebase.smsglobal.com/api-and-integration?hsLang=en-au) # REST API Error Codes  ## Common REST API error codes and troubleshooting steps to resolve them The following response codes apply to all requests. Check each request type in the list below for more response codes specific to that request. For more information, please see our [REST API Documentation.](http://smsglobal.com/rest-api/?_ga=1.75715861.1477567143.1488234285&hsLang=en-au) See below for details of error status codes, as well as the error meaning and description. --- **200** **OK** The request was processed successfully. **400** **Bad Request** Your request contained invalid or missing data. **401** **Unauthorized** Authentication failed, or the Authenticate header was not provided. **403** **HMAC-SHA Authentication Failed** Things to check for: - Ensure the REST API keys are correct, as well as the time they are authenticating with. - The URI is correct. - The computer/server must have accurate time as the authentication MAC is build using the time. Authentication will fail if the client computer time is different to our server time (not time-zone specific). - The time gap for successful authentication is within 30 seconds. - Also, check if the same nonce is in use for multiple requests. If the same nonce is used again, the request will return error 403. - To prevent replay attacks, a single nonce can only be used once. **404** **Not Found** The URI does not match any of the recognised resources, or if you are asking for a specific resource with an ID, that resource does not exist. **405** **Method Not Allowed** The HTTP request method you are trying to use is not allowed. Make an OPTIONS request to see the allowed methods. **406** **Not Acceptable** The Accept content type you are asking for is not supported by the REST API. **415** **Unsupported Media Type** The Content-Type header is not supported by the REST API. 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