--- a/netwerk/base/nsSocketTransportService2.cpp
+++ b/netwerk/base/nsSocketTransportService2.cpp
@@ -241,30 +241,24 @@ nsSocketTransportService::AttachSocket(P
 // limit the number of sockets that can be created by an application.
 // AttachSocket will fail if the limit is exceeded.  consumers should
 // call CanAttachSocket and check the result before creating a socket.
 
 bool
 nsSocketTransportService::CanAttachSocket()
 {
     static bool reported900FDLimit = false;
-    static bool reported256FDLimit = false;
 
     uint32_t total = mActiveCount + mIdleCount;
     bool rv = total < gMaxCount;
 
-    if (mTelemetryEnabledPref) {
-        if (((total >= 900) || !rv) && !reported900FDLimit) {
-            reported900FDLimit = true;
-            Telemetry::Accumulate(Telemetry::NETWORK_SESSION_AT_900FD, true);
-        }
-        if ((total >= 256) && !reported256FDLimit) {
-            reported256FDLimit = true;
-            Telemetry::Accumulate(Telemetry::NETWORK_SESSION_AT_256FD, true);
-        }
+    if (mTelemetryEnabledPref &&
+        (((total >= 900) || !rv) && !reported900FDLimit)) {
+        reported900FDLimit = true;
+        Telemetry::Accumulate(Telemetry::NETWORK_SESSION_AT_900FD, true);
     }
 
     return rv;
 }
 
 nsresult
 nsSocketTransportService::DetachSocket(SocketContext *listHead, SocketContext *sock)
 {

--- a/toolkit/components/telemetry/Histograms.json
+++ b/toolkit/components/telemetry/Histograms.json
@@ -2877,23 +2877,16 @@
     "kind": "boolean",
     "description": "The URL path contains !/"
   },
   "URL_PATH_CONTAINS_EXCLAMATION_DOUBLE_SLASH": {
     "expires_in_version": "never",
     "kind": "boolean",
     "description": "The URL path contains !//"
   },
-  "NETWORK_SESSION_AT_256FD": {
-    "expires_in_version": "49",
-    "kind": "boolean",
-    "description": "session exceeded old 256 limit",
-    "bug_numbers": [1260218],
-    "alert_emails": ["necko@mozilla.com"]
-  },
   "NETWORK_SESSION_AT_900FD": {
     "expires_in_version": "never",
     "kind": "boolean",
     "description": "session reached 900 fd limit sockets",
     "bug_numbers": [1260218],
     "alert_emails": ["necko@mozilla.com"]
   },
   "NETWORK_PROBE_MAXCOUNT": {