diff --git a/internal/proto/analytics/connections_log.proto b/internal/proto/analytics/connections_log.proto
index bc6702bb..408e18cc 100644
--- a/internal/proto/analytics/connections_log.proto
+++ b/internal/proto/analytics/connections_log.proto
@@ -340,7 +340,7 @@ message ConnectionsLog {
     optional string connection_token = 8;
   }
 
-  // Next Id: 20
+  // Next Id: 21
   message ErrorCode {
     // The direction (incoming vs outgoing) of this error.
     optional location.nearby.proto.connections.ConnectionAttemptDirection
@@ -376,6 +376,8 @@ message ConnectionsLog {
       location.nearby.errorcode.proto.ReceivePayloadError
           receive_payload_error = 18;
       location.nearby.errorcode.proto.UpgradeError upgrade_error = 19;
+      location.nearby.errorcode.proto.AcceptConnectionError
+          accept_connection_error = 20;
     }
 
     // The token use to identify this established connection.
diff --git a/proto/errorcode/error_code_enums.proto b/proto/errorcode/error_code_enums.proto
index 7cf8ae6d..e11e8557 100644
--- a/proto/errorcode/error_code_enums.proto
+++ b/proto/errorcode/error_code_enums.proto
@@ -360,6 +360,17 @@ enum UpgradeError {
   // Next ID :33
 }
 
+// The error for event ACCEPT_CONNECTION. The range between 31 and 99.
+enum AcceptConnectionError {
+  // The default value for clearcut
+  UNKNOWN_ACCEPT_CONNECTION_ERROR = 31;
+
+  // Network error, failed to send accept connection.
+  RESPOND_ACCEPT_CONNECTION_FAILED = 32;
+
+  // Next ID :33
+}
+
 enum Description {
   reserved 28, 29;