diff --git a/docshell/base/URIFixup.jsm b/docshell/base/URIFixup.jsm
index 8196c60e373d..001a43bf0964 100644
--- a/docshell/base/URIFixup.jsm
+++ b/docshell/base/URIFixup.jsm
@@ -55,13 +55,6 @@ XPCOMUtils.defineLazyServiceGetter(
   "nsIDNSService"
 );
 
-XPCOMUtils.defineLazyServiceGetter(
-  lazy,
-  "handlerService",
-  "@mozilla.org/uriloader/handler-service;1",
-  "nsIHandlerService"
-);
-
 XPCOMUtils.defineLazyPreferenceGetter(
   lazy,
   "fixupSchemeTypos",
@@ -266,15 +259,7 @@ XPCOMUtils.defineLazyGetter(lazy, "knownSuffixes", () => {
   return suffixes;
 });
 
-function URIFixup() {
-  // There are cases that nsIExternalProtocolService.externalProtocolHandlerExists() does
-  // not work well and returns always true due to flatpak. In this case, in order to
-  // fallback to nsIHandlerService.exits(), we test whether can trust
-  // nsIExternalProtocolService here.
-  this._trustExternalProtocolService = !lazy.externalProtocolService.externalProtocolHandlerExists(
-    `__dummy${Date.now()}__`
-  );
-}
+function URIFixup() {}
 
 URIFixup.prototype = {
   get FIXUP_FLAG_NONE() {
@@ -344,7 +329,7 @@ URIFixup.prototype = {
       scheme &&
       (isCommonProtocol ||
         Services.io.getProtocolHandler(scheme) != lazy.defaultProtocolHandler ||
-        this._isKnownExternalProtocol(scheme));
+        lazy.externalProtocolService.externalProtocolHandlerExists(scheme));
 
     if (
       canHandleProtocol ||
@@ -646,14 +631,6 @@ URIFixup.prototype = {
 
   isDomainKnown,
 
-  _isKnownExternalProtocol(scheme) {
-    return this._trustExternalProtocolService
-      ? lazy.externalProtocolService.externalProtocolHandlerExists(scheme)
-      : lazy.handlerService.exists(
-          lazy.externalProtocolService.getProtocolHandlerInfo(scheme)
-        );
-  },
-
   classID: Components.ID("{c6cf88b7-452e-47eb-bdc9-86e3561648ef}"),
   QueryInterface: ChromeUtils.generateQI(["nsIURIFixup"]),
 };
diff --git a/docshell/test/unit/test_URIFixup_external_protocol_fallback.js b/docshell/test/unit/test_URIFixup_external_protocol_fallback.js
deleted file mode 100644
index 61fa921cc881..000000000000
--- a/docshell/test/unit/test_URIFixup_external_protocol_fallback.js
+++ /dev/null
@@ -1,100 +0,0 @@
-/* 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/. */
-
-"use strict";
-
-// Test whether fallback mechanism is working if don't trust nsIExternalProtocolService.
-
-const { MockRegistrar } = ChromeUtils.import(
-  "resource://testing-common/MockRegistrar.jsm"
-);
-
-add_task(async function setup() {
-  info(
-    "Prepare mock nsIExternalProtocolService whose externalProtocolHandlerExists returns always true"
-  );
-  const externalProtocolService = Cc[
-    "@mozilla.org/uriloader/external-protocol-service;1"
-  ].getService(Ci.nsIExternalProtocolService);
-  const mockId = MockRegistrar.register(
-    "@mozilla.org/uriloader/external-protocol-service;1",
-    {
-      getProtocolHandlerInfo: scheme =>
-        externalProtocolService.getProtocolHandlerInfo(scheme),
-      externalProtocolHandlerExists: () => true,
-      QueryInterface: ChromeUtils.generateQI(["nsIExternalProtocolService"]),
-    }
-  );
-  const mockExternalProtocolService = Cc[
-    "@mozilla.org/uriloader/external-protocol-service;1"
-  ].getService(Ci.nsIExternalProtocolService);
-  Assert.ok(
-    mockExternalProtocolService.externalProtocolHandlerExists("__invalid__"),
-    "Mock service is working"
-  );
-
-  info("Register new dummy protocol");
-  const dummyProtocolHandlerInfo = externalProtocolService.getProtocolHandlerInfo(
-    "dummy"
-  );
-  const handlerService = Cc[
-    "@mozilla.org/uriloader/handler-service;1"
-  ].getService(Ci.nsIHandlerService);
-  handlerService.store(dummyProtocolHandlerInfo);
-
-  info("Prepare test search engine");
-  await setupSearchService();
-  await addTestEngines();
-  await Services.search.setDefault(
-    Services.search.getEngineByName(kSearchEngineID)
-  );
-
-  registerCleanupFunction(() => {
-    handlerService.remove(dummyProtocolHandlerInfo);
-    MockRegistrar.unregister(mockId);
-  });
-});
-
-add_task(function basic() {
-  const testData = [
-    {
-      input: "mailto:test@example.com",
-      expected: isSupportedInHandlerService("mailto")
-        ? "mailto:test@example.com"
-        : "http://mailto:test@example.com/",
-    },
-    {
-      input: "keyword:search",
-      expected: "https://www.example.org/?search=keyword%3Asearch",
-    },
-    {
-      input: "dummy:protocol",
-      expected: "dummy:protocol",
-    },
-  ];
-
-  for (const { input, expected } of testData) {
-    assertFixup(input, expected);
-  }
-});
-
-function assertFixup(input, expected) {
-  const { preferredURI } = Services.uriFixup.getFixupURIInfo(
-    input,
-    Services.uriFixup.FIXUP_FLAG_FIX_SCHEME_TYPOS
-  );
-  Assert.equal(preferredURI.spec, expected);
-}
-
-function isSupportedInHandlerService(scheme) {
-  const externalProtocolService = Cc[
-    "@mozilla.org/uriloader/external-protocol-service;1"
-  ].getService(Ci.nsIExternalProtocolService);
-  const handlerService = Cc[
-    "@mozilla.org/uriloader/handler-service;1"
-  ].getService(Ci.nsIHandlerService);
-  return handlerService.exists(
-    externalProtocolService.getProtocolHandlerInfo(scheme)
-  );
-}
diff --git a/docshell/test/unit/xpcshell.ini b/docshell/test/unit/xpcshell.ini
index 21e63c2228d0..21cf5f321dde 100644
--- a/docshell/test/unit/xpcshell.ini
+++ b/docshell/test/unit/xpcshell.ini
@@ -10,7 +10,6 @@ support-files =
 [test_browsing_context_structured_clone.js]
 [test_URIFixup.js]
 [test_URIFixup_check_host.js]
-[test_URIFixup_external_protocol_fallback.js]
 [test_URIFixup_forced.js]
 # Disabled for 1563343 -- URI fixup should be done at the app level in GV.
 skip-if = os == 'android'
@@ -25,6 +24,6 @@ skip-if =
 skip-if = true
 [test_privacy_transition.js]
 [test_subframe_stop_after_parent_error.js]
-skip-if =
+skip-if = 
   os == 'android'
   appname == 'thunderbird' # Needs to run without E10s, can't do that.