--- a/toolkit/mozapps/extensions/content/extensions.js
+++ b/toolkit/mozapps/extensions/content/extensions.js
@@ -33,23 +33,24 @@ ChromeUtils.defineModuleGetter(this, "Pr
 
 ChromeUtils.defineModuleGetter(this, "Experiments",
   "resource:///modules/experiments/Experiments.jsm");
 
 XPCOMUtils.defineLazyPreferenceGetter(this, "WEBEXT_PERMISSION_PROMPTS",
                                       "extensions.webextPermissionPrompts", false);
 XPCOMUtils.defineLazyPreferenceGetter(this, "ALLOW_NON_MPC",
                                       "extensions.allow-non-mpc-extensions", true);
+XPCOMUtils.defineLazyPreferenceGetter(this, "XPINSTALL_ENABLED",
+                                      "xpinstall.enabled", true);
 
 XPCOMUtils.defineLazyPreferenceGetter(this, "SUPPORT_URL", "app.support.baseURL",
                                       "", null, val => Services.urlFormatter.formatURL(val));
 
 const PREF_DISCOVERURL = "extensions.webservice.discoverURL";
 const PREF_DISCOVER_ENABLED = "extensions.getAddons.showPane";
-const PREF_XPI_ENABLED = "xpinstall.enabled";
 const PREF_GETADDONS_CACHE_ENABLED = "extensions.getAddons.cache.enabled";
 const PREF_GETADDONS_CACHE_ID_ENABLED = "extensions.%ID%.getAddons.cache.enabled";
 const PREF_UI_TYPE_HIDDEN = "extensions.ui.%TYPE%.hidden";
 const PREF_UI_LASTCATEGORY = "extensions.ui.lastCategory";
 const PREF_LEGACY_EXCEPTIONS = "extensions.legacy.exceptions";
 const PREF_LEGACY_ENABLED = "extensions.legacy.enabled";
 
 const LOADING_MSG_DELAY = 100;
@@ -159,16 +160,20 @@ function initialize(event) {
 
   gViewController.initialize();
   gCategories.initialize();
   gHeader.initialize();
   gEventManager.initialize();
   Services.obs.addObserver(sendEMPong, "EM-ping");
   Services.obs.notifyObservers(window, "EM-loaded");
 
+  if (!XPINSTALL_ENABLED) {
+    document.getElementById("cmd_installFromFile").hidden = true;
+  }
+
   // If the initial view has already been selected (by a call to loadView from
   // the above notifications) then bail out now
   if (gViewController.initialViewSelected)
     return;
 
   // If there is a history state to restore then use that
   if (window.history.state) {
     gViewController.updateState(window.history.state);
@@ -265,20 +270,19 @@ function isDiscoverEnabled() {
   if (Services.prefs.getPrefType(PREF_DISCOVERURL) == Services.prefs.PREF_INVALID)
     return false;
 
   try {
     if (!Services.prefs.getBoolPref(PREF_DISCOVER_ENABLED))
       return false;
   } catch (e) {}
 
-  try {
-    if (!Services.prefs.getBoolPref(PREF_XPI_ENABLED))
-      return false;
-  } catch (e) {}
+  if (!XPINSTALL_ENABLED) {
+    return false;
+  }
 
   return true;
 }
 
 function getExperimentEndDate(aAddon) {
   if (!("@mozilla.org/browser/experiments-service;1" in Cc)) {
     return 0;
   }
@@ -1310,17 +1314,17 @@ var gViewController = {
       },
       doCommand(aAddon) {
         aAddon.cancelUninstall();
       }
     },
 
     cmd_installFromFile: {
       isEnabled() {
-        return true;
+        return XPINSTALL_ENABLED;
       },
       doCommand() {
         const nsIFilePicker = Ci.nsIFilePicker;
         var fp = Cc["@mozilla.org/filepicker;1"]
                    .createInstance(nsIFilePicker);
         fp.init(window,
                 gStrings.ext.GetStringFromName("installFromFile.dialogTitle"),
                 nsIFilePicker.modeOpenMultiple);
@@ -3615,16 +3619,20 @@ var gUpdatesView = {
   onPropertyChanged(aAddon, aProperties) {
     if (aProperties.includes("applyBackgroundUpdates"))
       this.updateAvailableCount();
   }
 };
 
 var gDragDrop = {
   onDragOver(aEvent) {
+    if (!XPINSTALL_ENABLED) {
+      aEvent.dataTransfer.effectAllowed = "none";
+      return;
+    }
     var types = aEvent.dataTransfer.types;
     if (types.includes("text/uri-list") ||
         types.includes("text/x-moz-url") ||
         types.includes("application/x-moz-file"))
       aEvent.preventDefault();
   },
 
   onDrop(aEvent) {