diff --git a/browser/components/extensions/parent/ext-history.js b/browser/components/extensions/parent/ext-history.js
index 6ab1912d2591..fe9afdf3c43d 100644
--- a/browser/components/extensions/parent/ext-history.js
+++ b/browser/components/extensions/parent/ext-history.js
@@ -104,7 +104,6 @@ const getHistoryObserver = () => {
       }
       onBeginUpdateBatch() {}
       onEndUpdateBatch() {}
-      onManyFrecenciesChanged() {}
       onDeleteVisits(uri, partialRemoval, guid, reason) {
         if (!partialRemoval) {
           this.emit("visitRemoved", { allHistory: false, urls: [uri.spec] });
diff --git a/browser/components/newtab/lib/PlacesFeed.jsm b/browser/components/newtab/lib/PlacesFeed.jsm
index 6022a4233af3..e76fc780008e 100644
--- a/browser/components/newtab/lib/PlacesFeed.jsm
+++ b/browser/components/newtab/lib/PlacesFeed.jsm
@@ -73,8 +73,6 @@ class HistoryObserver extends Observer {
 
   onEndUpdateBatch() {}
 
-  onManyFrecenciesChanged() {}
-
   onDeleteVisits() {}
 }
 
diff --git a/browser/components/newtab/test/unit/lib/PlacesFeed.test.js b/browser/components/newtab/test/unit/lib/PlacesFeed.test.js
index 349f7fef457b..3790fc99b846 100644
--- a/browser/components/newtab/test/unit/lib/PlacesFeed.test.js
+++ b/browser/components/newtab/test/unit/lib/PlacesFeed.test.js
@@ -766,7 +766,6 @@ describe("PlacesFeed", () => {
       it("should have a various empty functions for xpconnect happiness", () => {
         observer.onBeginUpdateBatch();
         observer.onEndUpdateBatch();
-        observer.onManyFrecenciesChanged();
         observer.onDeleteVisits();
       });
     });
diff --git a/services/sync/tests/unit/head_helpers.js b/services/sync/tests/unit/head_helpers.js
index be59e46e3773..3d51dbf03889 100644
--- a/services/sync/tests/unit/head_helpers.js
+++ b/services/sync/tests/unit/head_helpers.js
@@ -633,7 +633,6 @@ async function promiseVisit(expectedType, expectedURI) {
       },
       onBeginUpdateBatch() {},
       onEndUpdateBatch() {},
-      onManyFrecenciesChanged() {},
       onDeleteURI(uri) {
         done("removed", uri.spec);
       },
diff --git a/toolkit/components/downloads/DownloadHistory.jsm b/toolkit/components/downloads/DownloadHistory.jsm
index 12d458a0533a..b806e0f62739 100644
--- a/toolkit/components/downloads/DownloadHistory.jsm
+++ b/toolkit/components/downloads/DownloadHistory.jsm
@@ -345,7 +345,6 @@ var DownloadCache = {
   },
   onBeginUpdateBatch() {},
   onEndUpdateBatch() {},
-  onManyFrecenciesChanged() {},
   onDeleteVisits() {},
 };
 
diff --git a/toolkit/components/places/nsINavHistoryService.idl b/toolkit/components/places/nsINavHistoryService.idl
index fa9327ef601e..562d849d9192 100644
--- a/toolkit/components/places/nsINavHistoryService.idl
+++ b/toolkit/components/places/nsINavHistoryService.idl
@@ -579,13 +579,6 @@ interface nsINavHistoryObserver : nsISupports
    */
   void onEndUpdateBatch();
 
-  /**
-   * Called when the frecencies of many pages have changed at once.
-   *
-   * onFrecencyChanged is not called for each of those pages.
-   */
-  void onManyFrecenciesChanged();
-
   /**
    * Removed by the user.
    */
diff --git a/toolkit/components/places/nsNavHistoryResult.cpp b/toolkit/components/places/nsNavHistoryResult.cpp
index 536e71fd986b..a23c10d6d488 100644
--- a/toolkit/components/places/nsNavHistoryResult.cpp
+++ b/toolkit/components/places/nsNavHistoryResult.cpp
@@ -2257,9 +2257,6 @@ nsresult nsNavHistoryQueryResultNode::OnTitleChanged(
   return ChangeTitles(aURI, newTitle, true, onlyOneEntry);
 }
 
-NS_IMETHODIMP
-nsNavHistoryQueryResultNode::OnManyFrecenciesChanged() { return NS_OK; }
-
 /**
  * Here, we can always live update by just deleting all occurrences of
  * the given URI.
@@ -4214,9 +4211,6 @@ void nsNavHistoryResult::HandlePlacesEvent(const PlacesEventSequence& aEvents) {
   }
 }
 
-NS_IMETHODIMP
-nsNavHistoryResult::OnManyFrecenciesChanged() { return NS_OK; }
-
 NS_IMETHODIMP
 nsNavHistoryResult::OnDeleteURI(nsIURI* aURI, const nsACString& aGUID,
                                 uint16_t aReason) {
diff --git a/toolkit/components/places/nsNavHistoryResult.h b/toolkit/components/places/nsNavHistoryResult.h
index 9ef874774349..bef36ed051c2 100644
--- a/toolkit/components/places/nsNavHistoryResult.h
+++ b/toolkit/components/places/nsNavHistoryResult.h
@@ -64,7 +64,6 @@ class nsTrimInt64HashKey : public PLDHashEntryHdr {
 // and nsINavHistoryObserver (some methods, such as BeginUpdateBatch overlap)
 #define NS_DECL_BOOKMARK_HISTORY_OBSERVER_BASE(...)                    \
   NS_DECL_NSINAVBOOKMARKOBSERVER                                       \
-  NS_IMETHOD OnManyFrecenciesChanged() __VA_ARGS__;                    \
   NS_IMETHOD OnDeleteURI(nsIURI* aURI, const nsACString& aGUID,        \
                          uint16_t aReason) __VA_ARGS__;                \
   NS_IMETHOD OnDeleteVisits(nsIURI* aURI, bool aPartialRemoval,        \
diff --git a/toolkit/components/places/tests/history/test_remove.js b/toolkit/components/places/tests/history/test_remove.js
index 87adfcc97187..2d1f923fdcd2 100644
--- a/toolkit/components/places/tests/history/test_remove.js
+++ b/toolkit/components/places/tests/history/test_remove.js
@@ -45,13 +45,6 @@ add_task(async function test_remove_single() {
       observer = {
         onBeginUpdateBatch() {},
         onEndUpdateBatch() {},
-        onManyFrecenciesChanged() {
-          try {
-            Assert.ok(!shouldRemove, "Observing onManyFrecenciesChanged");
-          } finally {
-            resolve();
-          }
-        },
         onDeleteURI(aURI) {
           try {
             Assert.ok(shouldRemove, "Observing onDeleteURI");
diff --git a/toolkit/components/places/tests/history/test_removeByFilter.js b/toolkit/components/places/tests/history/test_removeByFilter.js
index bedf8ebef270..2e6746f61ed6 100644
--- a/toolkit/components/places/tests/history/test_removeByFilter.js
+++ b/toolkit/components/places/tests/history/test_removeByFilter.js
@@ -464,7 +464,6 @@ function getObserverPromise(bookmarkedUri) {
     observer = {
       onBeginUpdateBatch() {},
       onEndUpdateBatch() {},
-      onManyFrecenciesChanged() {},
       onDeleteURI(aURI) {
         try {
           Assert.notEqual(
diff --git a/toolkit/components/places/tests/history/test_removeMany.js b/toolkit/components/places/tests/history/test_removeMany.js
index 8d89daef4b60..14f54385a459 100644
--- a/toolkit/components/places/tests/history/test_removeMany.js
+++ b/toolkit/components/places/tests/history/test_removeMany.js
@@ -83,7 +83,6 @@ add_task(async function test_remove_many() {
     onVisits(aVisits) {
       Assert.ok(false, "Unexpected call to onVisits " + aVisits.length);
     },
-    onManyFrecenciesChanged() {},
     onDeleteURI(aURI) {
       let origin = pages.find(x => x.uri.spec == aURI.spec);
       Assert.ok(origin);
diff --git a/toolkit/components/places/tests/history/test_removeVisitsByFilter.js b/toolkit/components/places/tests/history/test_removeVisitsByFilter.js
index aa97778501c1..23468ee7af62 100644
--- a/toolkit/components/places/tests/history/test_removeVisitsByFilter.js
+++ b/toolkit/components/places/tests/history/test_removeVisitsByFilter.js
@@ -144,12 +144,6 @@ add_task(async function test_removeVisitsByFilter() {
       deferred: PromiseUtils.defer(),
       onBeginUpdateBatch() {},
       onEndUpdateBatch() {},
-      onManyFrecenciesChanged() {
-        info("Many frecencies changed");
-        for (let [, deferred] of rankingChangePromises) {
-          deferred.resolve();
-        }
-      },
       onDeleteURI(aURI) {
         info("onDeleteURI " + aURI.spec);
         let deferred = uriDeletePromises.get(aURI.spec);