From 80019f60cd1972057bf68593eef0c1ebb97eb0b8 Mon Sep 17 00:00:00 2001
From: Oleksandr Poliakov <oleksandr.poliakov@mongodb.com>
Date: Wed, 18 Mar 2026 10:05:09 -0700
Subject: [PATCH] CSHARP-5871: Clarify phase description for "Network timeouts
 test" spec test

---
 .../tests/errors/error_handling_handshake.json | 18 +++++++++++++-----
 .../tests/errors/error_handling_handshake.yml  | 15 ++++-----------
 .../ServerDiscoveryAndMonitoringTestRunner.cs  |  1 +
 3 files changed, 18 insertions(+), 16 deletions(-)

diff --git a/specifications/server-discovery-and-monitoring/tests/errors/error_handling_handshake.json b/specifications/server-discovery-and-monitoring/tests/errors/error_handling_handshake.json
index 56ca7d11328..c60ee453dd3 100644
--- a/specifications/server-discovery-and-monitoring/tests/errors/error_handling_handshake.json
+++ b/specifications/server-discovery-and-monitoring/tests/errors/error_handling_handshake.json
@@ -85,7 +85,7 @@
       }
     },
     {
-      "description": "Mark server unknown on network timeout application error (beforeHandshakeCompletes)",
+      "description": "Ignore network timeout application error (beforeHandshakeCompletes)",
       "applicationErrors": [
         {
           "address": "a:27017",
@@ -97,14 +97,22 @@
       "outcome": {
         "servers": {
           "a:27017": {
-            "type": "Unknown",
-            "topologyVersion": null,
+            "type": "RSPrimary",
+            "setName": "rs",
+            "topologyVersion": {
+              "processId": {
+                "$oid": "000000000000000000000001"
+              },
+              "counter": {
+                "$numberLong": "1"
+              }
+            },
             "pool": {
-              "generation": 1
+              "generation": 0
             }
           }
         },
-        "topologyType": "ReplicaSetNoPrimary",
+        "topologyType": "ReplicaSetWithPrimary",
         "logicalSessionTimeoutMinutes": null,
         "setName": "rs"
       }
diff --git a/specifications/server-discovery-and-monitoring/tests/errors/error_handling_handshake.yml b/specifications/server-discovery-and-monitoring/tests/errors/error_handling_handshake.yml
index 8482ea704c2..42cfa60509c 100644
--- a/specifications/server-discovery-and-monitoring/tests/errors/error_handling_handshake.yml
+++ b/specifications/server-discovery-and-monitoring/tests/errors/error_handling_handshake.yml
@@ -37,19 +37,12 @@ phases:
     type: timeout
   outcome: *outcome
 
-- description: Mark server unknown on network timeout application error (beforeHandshakeCompletes)
+- description: Ignore network timeout application error (beforeHandshakeCompletes)
+  # The test runner may need to add the SystemOverloadedError label for the pre-handshake network timeout.
+  # The SystemOverloadedError label causes the error to be ignored.
   applicationErrors:
   - address: a:27017
     when: beforeHandshakeCompletes
     maxWireVersion: 9
     type: timeout
-  outcome:
-    servers:
-      a:27017:
-        type: Unknown
-        topologyVersion: null
-        pool:
-          generation: 1
-    topologyType: ReplicaSetNoPrimary
-    logicalSessionTimeoutMinutes: null
-    setName: rs
+  outcome: *outcome
\ No newline at end of file
diff --git a/tests/MongoDB.Driver.Tests/Specifications/server-discovery-and-monitoring/ServerDiscoveryAndMonitoringTestRunner.cs b/tests/MongoDB.Driver.Tests/Specifications/server-discovery-and-monitoring/ServerDiscoveryAndMonitoringTestRunner.cs
index 9fc61009e7b..62da51346e7 100644
--- a/tests/MongoDB.Driver.Tests/Specifications/server-discovery-and-monitoring/ServerDiscoveryAndMonitoringTestRunner.cs
+++ b/tests/MongoDB.Driver.Tests/Specifications/server-discovery-and-monitoring/ServerDiscoveryAndMonitoringTestRunner.cs
@@ -103,6 +103,7 @@ private void ApplyApplicationError(BsonDocument applicationError)
                     {
                         var innerException = CoreExceptionHelper.CreateException("IOExceptionWithTimedOutSocketException");
                         simulatedException = new MongoConnectionException(connectionId, "Chaos, yet harmony.", innerException);
+                        ((MongoConnectionException)simulatedException).AddErrorLabel("SystemOverloadedError");
                         break;
                     }
                 default: