--- a/browser/app/profile/firefox.js
+++ b/browser/app/profile/firefox.js
@@ -736,36 +736,16 @@ pref("browser.backspace_action", 0);
 // editable elements in HTML
 // 0 = spellcheck nothing
 // 1 = check multi-line controls [default]
 // 2 = check multi/single line controls
 pref("layout.spellcheckDefault", 1);
 
 pref("browser.send_pings", false);
 
-/* initial web feed readers list */
-pref("browser.contentHandlers.types.0.title", "chrome://browser-region/locale/region.properties");
-pref("browser.contentHandlers.types.0.uri", "chrome://browser-region/locale/region.properties");
-pref("browser.contentHandlers.types.0.type", "application/vnd.mozilla.maybe.feed");
-pref("browser.contentHandlers.types.1.title", "chrome://browser-region/locale/region.properties");
-pref("browser.contentHandlers.types.1.uri", "chrome://browser-region/locale/region.properties");
-pref("browser.contentHandlers.types.1.type", "application/vnd.mozilla.maybe.feed");
-pref("browser.contentHandlers.types.2.title", "chrome://browser-region/locale/region.properties");
-pref("browser.contentHandlers.types.2.uri", "chrome://browser-region/locale/region.properties");
-pref("browser.contentHandlers.types.2.type", "application/vnd.mozilla.maybe.feed");
-pref("browser.contentHandlers.types.3.title", "chrome://browser-region/locale/region.properties");
-pref("browser.contentHandlers.types.3.uri", "chrome://browser-region/locale/region.properties");
-pref("browser.contentHandlers.types.3.type", "application/vnd.mozilla.maybe.feed");
-pref("browser.contentHandlers.types.4.title", "chrome://browser-region/locale/region.properties");
-pref("browser.contentHandlers.types.4.uri", "chrome://browser-region/locale/region.properties");
-pref("browser.contentHandlers.types.4.type", "application/vnd.mozilla.maybe.feed");
-pref("browser.contentHandlers.types.5.title", "chrome://browser-region/locale/region.properties");
-pref("browser.contentHandlers.types.5.uri", "chrome://browser-region/locale/region.properties");
-pref("browser.contentHandlers.types.5.type", "application/vnd.mozilla.maybe.feed");
-
 pref("browser.feeds.handler", "ask");
 pref("browser.videoFeeds.handler", "ask");
 pref("browser.audioFeeds.handler", "ask");
 
 // At startup, if the handler service notices that the version number in the
 // region.properties file is newer than the version number in the handler
 // service datastore, it will add any new handlers it finds in the prefs (as
 // seeded by this file) to its datastore.

--- a/browser/components/nsBrowserGlue.js
+++ b/browser/components/nsBrowserGlue.js
@@ -1806,17 +1806,17 @@ BrowserGlue.prototype = {
       }
     }
   },
 
   // eslint-disable-next-line complexity
   _migrateUI: function BG__migrateUI() {
     // Use an increasing number to keep track of the current migration state.
     // Completely unrelated to the current Firefox release number.
-    const UI_VERSION = 70;
+    const UI_VERSION = 71;
     const BROWSER_DOCURL = AppConstants.BROWSER_CHROME_URL;
 
     let currentUIVersion;
     if (Services.prefs.prefHasUserValue("browser.migration.version")) {
       currentUIVersion = Services.prefs.getIntPref("browser.migration.version");
     } else {
       // This is a new profile, nothing to migrate.
       Services.prefs.setIntPref("browser.migration.version", UI_VERSION);
@@ -2129,16 +2129,24 @@ BrowserGlue.prototype = {
       Services.prefs.setBoolPref("browser.ctrlTab.recentlyUsedOrder",
         Services.prefs.getBoolPref("browser.ctrlTab.previews", false));
       Services.prefs.clearUserPref("browser.ctrlTab.previews");
       // Remember that we migrated the pref in case we decide to flip it for
       // these users.
       Services.prefs.setBoolPref("browser.ctrlTab.migrated", true);
     }
 
+    if (currentUIVersion < 71) {
+      // Clear legacy saved prefs for content handlers.
+      let savedContentHandlers = Services.prefs.getChildList("browser.contentHandlers.types");
+      for (let savedHandlerPref of savedContentHandlers) {
+        Services.prefs.clearUserPref(savedHandlerPref);
+      }
+    }
+
     // Update the migration version.
     Services.prefs.setIntPref("browser.migration.version", UI_VERSION);
   },
 
   _checkForDefaultBrowser() {
     // Perform default browser checking.
     if (!ShellService) {
       return;

--- a/browser/locales/en-US/chrome/browser-region/region.properties
+++ b/browser/locales/en-US/chrome/browser-region/region.properties
@@ -1,17 +1,12 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
-# This is the default set of web based feed handlers shown in the reader
-# selection UI
-browser.contentHandlers.types.0.title=My Yahoo!
-browser.contentHandlers.types.0.uri=https://add.my.yahoo.com/rss?url=%s
-
 # increment this number when anything gets changed in the list below.  This will
 # cause Firefox to re-read these prefs and inject any new handlers into the 
 # profile database.  Note that "new" is defined as "has a different URL"; this
 # means that it's not possible to update the name of existing handler, so 
 # don't make any spelling errors here.
 gecko.handlerService.defaultHandlersVersion=4
 
 # The default set of protocol handlers for webcal: