1e41f4b71Sopenharmony_ci# mDNS Error Codes 2e41f4b71Sopenharmony_ci 3e41f4b71Sopenharmony_ci> **NOTE** 4e41f4b71Sopenharmony_ci> 5e41f4b71Sopenharmony_ci> This topic describes only module-specific error codes. For details about universal error codes, see [Universal Error Codes](../errorcode-universal.md). 6e41f4b71Sopenharmony_ci 7e41f4b71Sopenharmony_ci## 2100002 Service Connection Failure 8e41f4b71Sopenharmony_ci 9e41f4b71Sopenharmony_ci**Error Message** 10e41f4b71Sopenharmony_ci 11e41f4b71Sopenharmony_ciFailed to connect to the service. 12e41f4b71Sopenharmony_ci 13e41f4b71Sopenharmony_ci**Description** 14e41f4b71Sopenharmony_ci 15e41f4b71Sopenharmony_ciThis error code is reported if a service connection failure occurs. 16e41f4b71Sopenharmony_ci 17e41f4b71Sopenharmony_ci**Possible Causes** 18e41f4b71Sopenharmony_ci 19e41f4b71Sopenharmony_ciThe service is abnormal. 20e41f4b71Sopenharmony_ci 21e41f4b71Sopenharmony_ci**Procedure** 22e41f4b71Sopenharmony_ci 23e41f4b71Sopenharmony_ciCheck whether system services are running properly. 24e41f4b71Sopenharmony_ci 25e41f4b71Sopenharmony_ci## 2100003 System Internal Error 26e41f4b71Sopenharmony_ci 27e41f4b71Sopenharmony_ci**Error Message** 28e41f4b71Sopenharmony_ci 29e41f4b71Sopenharmony_ciSystem internal error. 30e41f4b71Sopenharmony_ci 31e41f4b71Sopenharmony_ci**Description** 32e41f4b71Sopenharmony_ci 33e41f4b71Sopenharmony_ciThis error code is reported if a system internal error occurs. 34e41f4b71Sopenharmony_ci 35e41f4b71Sopenharmony_ci**Possible Causes** 36e41f4b71Sopenharmony_ci 37e41f4b71Sopenharmony_ci1. The memory is abnormal. 38e41f4b71Sopenharmony_ci 39e41f4b71Sopenharmony_ci2. A null pointer is present. 40e41f4b71Sopenharmony_ci 41e41f4b71Sopenharmony_ci**Procedure** 42e41f4b71Sopenharmony_ci 43e41f4b71Sopenharmony_ci1. Check whether the memory space is sufficient. If not, clear the memory and try again. 44e41f4b71Sopenharmony_ci 45e41f4b71Sopenharmony_ci2. Check whether the system is normal. If not, try again later or restart the device. 46e41f4b71Sopenharmony_ci 47e41f4b71Sopenharmony_ci## 2204003 Repeated Registration 48e41f4b71Sopenharmony_ci 49e41f4b71Sopenharmony_ci**Error Message** 50e41f4b71Sopenharmony_ci 51e41f4b71Sopenharmony_ciCallback duplicated. 52e41f4b71Sopenharmony_ci 53e41f4b71Sopenharmony_ci**Description** 54e41f4b71Sopenharmony_ci 55e41f4b71Sopenharmony_ciThis error code is reported if a callback already exists. 56e41f4b71Sopenharmony_ci 57e41f4b71Sopenharmony_ci**Possible Causes** 58e41f4b71Sopenharmony_ci 59e41f4b71Sopenharmony_ciAn mDNS service with the same name and type is repeatedly registered. 60e41f4b71Sopenharmony_ci 61e41f4b71Sopenharmony_ci**Procedure** 62e41f4b71Sopenharmony_ci 63e41f4b71Sopenharmony_ciCheck whether the mDNS service to be registered already exists. 64e41f4b71Sopenharmony_ci 65e41f4b71Sopenharmony_ci## 2204007 Service Already Exists 66e41f4b71Sopenharmony_ci 67e41f4b71Sopenharmony_ci**Error Message** 68e41f4b71Sopenharmony_ci 69e41f4b71Sopenharmony_ciService instance duplicated. 70e41f4b71Sopenharmony_ci 71e41f4b71Sopenharmony_ci**Description** 72e41f4b71Sopenharmony_ci 73e41f4b71Sopenharmony_ciThis error code is reported if an mDNS service already exists. 74e41f4b71Sopenharmony_ci 75e41f4b71Sopenharmony_ci**Possible Causes** 76e41f4b71Sopenharmony_ci 77e41f4b71Sopenharmony_ciThe previously registered mDNS service is still running. 78e41f4b71Sopenharmony_ci 79e41f4b71Sopenharmony_ci**Procedure** 80e41f4b71Sopenharmony_ci 81e41f4b71Sopenharmony_ciCheck whether the mDNS service already exists. 82e41f4b71Sopenharmony_ci 83e41f4b71Sopenharmony_ci## 2204008 Service Deletion Failure 84e41f4b71Sopenharmony_ci 85e41f4b71Sopenharmony_ci**Error Message** 86e41f4b71Sopenharmony_ci 87e41f4b71Sopenharmony_ciFailed to delete the service instance. 88e41f4b71Sopenharmony_ci 89e41f4b71Sopenharmony_ci**Description** 90e41f4b71Sopenharmony_ci 91e41f4b71Sopenharmony_ciThis error code is reported if the mDNS service to be removed does not exist. 92e41f4b71Sopenharmony_ci 93e41f4b71Sopenharmony_ci**Possible Causes** 94e41f4b71Sopenharmony_ci 95e41f4b71Sopenharmony_ciThe service has been deleted. 96e41f4b71Sopenharmony_ci 97e41f4b71Sopenharmony_ci**Procedure** 98e41f4b71Sopenharmony_ci 99e41f4b71Sopenharmony_ciCheck whether the mDNS service to be deleted exists. 100e41f4b71Sopenharmony_ci 101e41f4b71Sopenharmony_ci## 2204010 Message Sending Failure 102e41f4b71Sopenharmony_ci 103e41f4b71Sopenharmony_ci**Error Message** 104e41f4b71Sopenharmony_ci 105e41f4b71Sopenharmony_ciFailed to send the message. 106e41f4b71Sopenharmony_ci 107e41f4b71Sopenharmony_ci**Description** 108e41f4b71Sopenharmony_ci 109e41f4b71Sopenharmony_ciThis error code is reported if messages fail to be sent through an mDNS service. 110e41f4b71Sopenharmony_ci 111e41f4b71Sopenharmony_ci**Possible Causes** 112e41f4b71Sopenharmony_ci 113e41f4b71Sopenharmony_ciThe mDNS service does not exist on the LAN. 114e41f4b71Sopenharmony_ci 115e41f4b71Sopenharmony_ci**Procedure** 116e41f4b71Sopenharmony_ci 117e41f4b71Sopenharmony_ciCheck whether the target mDNS service exists on the LAN. 118e41f4b71Sopenharmony_ci 119e41f4b71Sopenharmony_ci## 2204006 Service Resolution Timeout 120e41f4b71Sopenharmony_ci 121e41f4b71Sopenharmony_ci**Error Message** 122e41f4b71Sopenharmony_ci 123e41f4b71Sopenharmony_ciRequest timeout. 124e41f4b71Sopenharmony_ci 125e41f4b71Sopenharmony_ci**Description** 126e41f4b71Sopenharmony_ci 127e41f4b71Sopenharmony_ciThis error code is reported if mDNS services of the specified type fail to be resolved. 128e41f4b71Sopenharmony_ci 129e41f4b71Sopenharmony_ci**Possible Causes** 130e41f4b71Sopenharmony_ci 131e41f4b71Sopenharmony_cimDNS services of the specified type do not exist on the LAN. 132e41f4b71Sopenharmony_ci 133e41f4b71Sopenharmony_ci**Procedure** 134e41f4b71Sopenharmony_ci 135e41f4b71Sopenharmony_ciCheck whether mDNS services of the specified type exist on the LAN. 136