If the MQ for MQTT API is called successfully, ResponseCode=200 is returned to the MQTT client. If the call fails, error codes and descriptions are returned. You can find a solution based on the following error messages.
| Error code | Symptom and cause | Solution |
|---|---|---|
| ONS_SYSTEM_ERROR | The backend of MQ is abnormal. | Contact Alibaba Cloud Customer Services by submitting a ticket. |
| ONS_SERVICE_UNSUPPORTED | The call is not currently supported in the corresponding region. | Contact Alibaba Cloud Customer Services to check whether the operation is available. |
| ONS_INVOKE_ERROR | API call failed. | Contact Alibaba Cloud Customer Services. |
| BIZ_FIELD_CHECK_INVALID | Parameter verification failed. | Check whether the parameters are valid based on the API reference. |
| BIZ_TOPIC_NOT_FOUND | The topic cannot be found. | Check whether the entered topic is valid or available. |
| BIZ_SUBSCRIPTION_NOT_FOUND | The target subscription group ID cannot be found. | Check whether the group ID exists or whether the filter is correct. |
| BIZ_PUBLISHER_EXISTED | The specified group ID already exists. | Try again with a new group ID. |
| BIZ_SUBSCRIPTION_EXISTED | The specified group ID already exists. | Try again with a new group ID. |
| BIZ_CONSUMER_NOT_ONLINE | The client with the specified group ID is offline. | Ensure that the consumer client exists and then try again. |
| BIZ_NO_MESSAGE | No message matches the filter. | Check the filter and check whether messages have been published in the query range. |
| BIZ_REGION_NOT_FOUND | The region where you request the service cannot be found. | Check whether the parameters for the region where you request the service are valid. |
| BIZ_TOPIC_EXISTED | The specified topic already exists. | Try again with a new topic name. |
| BIZ_PUBLISH_INFO_NOT_FOUND | The requested group ID cannot be found. | Check whether the group ID exists or whether the request condition is correct. |
| EMPOWER_EXIST_ERROR | The current authorization already exists. | Verify the request parameters and try again or query the authorization. |
| EMPOWER_OWNER_CHECK_ERROR | The current user is not the owner of the topic to be authorized. | Check the ownership of the resource. |