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