--- a/toolkit/components/telemetry/Histograms.json
+++ b/toolkit/components/telemetry/Histograms.json
@@ -3648,21 +3648,16 @@
   },
   "URLCLASSIFIER_LC_COMPLETIONS": {
     "expires_in_version": "never",
     "kind": "exponential",
     "high": 200,
     "n_buckets": 10,
     "description": "Size of the completion cache in entries"
   },
-  "URLCLASSIFIER_PS_FAILURE": {
-    "expires_in_version": "default",
-    "kind": "boolean",
-    "description": "Did UrlClassifier fail to construct the PrefixSet?"
-  },
   "URLCLASSIFIER_UPDATE_REMOTE_STATUS": {
     "alert_emails": ["gcp@mozilla.com", "francois@mozilla.com"],
     "expires_in_version": "never",
     "kind": "enumerated",
     "n_values": 16,
     "bug_numbers": [1150921],
     "description": "Server HTTP status code from SafeBrowsing database updates. (0=1xx, 1=200, 2=2xx, 3=204, 4=3xx, 5=400, 6=4xx, 7=403, 8=404, 9=408, 10=413, 11=5xx, 12=502|504|511, 13=503, 14=505, 15=Other)"
   },

--- a/toolkit/components/telemetry/histogram-whitelists.json
+++ b/toolkit/components/telemetry/histogram-whitelists.json
@@ -757,17 +757,16 @@
     "TRANSLATION_OPPORTUNITIES",
     "TRANSLATION_OPPORTUNITIES_BY_LANGUAGE",
     "URLCLASSIFIER_CL_CHECK_TIME",
     "URLCLASSIFIER_CL_UPDATE_TIME",
     "URLCLASSIFIER_LC_COMPLETIONS",
     "URLCLASSIFIER_LC_PREFIXES",
     "URLCLASSIFIER_LOOKUP_TIME",
     "URLCLASSIFIER_PS_CONSTRUCT_TIME",
-    "URLCLASSIFIER_PS_FAILURE",
     "URLCLASSIFIER_PS_FALLOCATE_TIME",
     "URLCLASSIFIER_PS_FILELOAD_TIME",
     "VIDEO_CANPLAYTYPE_H264_CONSTRAINT_SET_FLAG",
     "VIDEO_CANPLAYTYPE_H264_LEVEL",
     "VIDEO_CANPLAYTYPE_H264_PROFILE",
     "VIDEO_DECODED_H264_SPS_CONSTRAINT_SET_FLAG",
     "VIDEO_DECODED_H264_SPS_LEVEL",
     "VIDEO_DECODED_H264_SPS_PROFILE",
@@ -1826,17 +1825,16 @@
     "UPDATE_UNABLE_TO_APPLY_NOTIFY",
     "UPDATE_WIZ_LAST_PAGE_CODE",
     "URLCLASSIFIER_CL_CHECK_TIME",
     "URLCLASSIFIER_CL_UPDATE_TIME",
     "URLCLASSIFIER_LC_COMPLETIONS",
     "URLCLASSIFIER_LC_PREFIXES",
     "URLCLASSIFIER_LOOKUP_TIME",
     "URLCLASSIFIER_PS_CONSTRUCT_TIME",
-    "URLCLASSIFIER_PS_FAILURE",
     "URLCLASSIFIER_PS_FALLOCATE_TIME",
     "URLCLASSIFIER_PS_FILELOAD_TIME",
     "VIDEO_CANPLAYTYPE_H264_CONSTRAINT_SET_FLAG",
     "VIDEO_CANPLAYTYPE_H264_LEVEL",
     "VIDEO_CANPLAYTYPE_H264_PROFILE",
     "VIDEO_CAN_CREATE_AAC_DECODER",
     "VIDEO_CAN_CREATE_H264_DECODER",
     "VIDEO_DECODED_H264_SPS_CONSTRAINT_SET_FLAG",

--- a/toolkit/components/url-classifier/LookupCache.cpp
+++ b/toolkit/components/url-classifier/LookupCache.cpp
@@ -469,33 +469,27 @@ LookupCache::ConstructPrefixSet(AddPrefi
 
 #ifdef DEBUG
   // PrefixSet requires sorted order
   EnsureSorted(&array);
 #endif
 
   // construct new one, replace old entries
   nsresult rv = mPrefixSet->SetPrefixes(array.Elements(), array.Length());
-  if (NS_FAILED(rv)) {
-    goto error_bailout;
-  }
+  NS_ENSURE_SUCCESS(rv, rv);
 
 #ifdef DEBUG
   uint32_t size;
   size = mPrefixSet->SizeOfIncludingThis(moz_malloc_size_of);
   LOG(("SB tree done, size = %d bytes\n", size));
 #endif
 
   mPrimed = true;
 
   return NS_OK;
-
- error_bailout:
-  Telemetry::Accumulate(Telemetry::URLCLASSIFIER_PS_FAILURE, 1);
-  return rv;
 }
 
 nsresult
 LookupCache::LoadPrefixSet()
 {
   nsCOMPtr<nsIFile> psFile;
   nsresult rv = mStoreDirectory->Clone(getter_AddRefs(psFile));
   NS_ENSURE_SUCCESS(rv, rv);