diff --git a/browser/base/content/browser.js b/browser/base/content/browser.js
index 3873318dfee4..76ba6806aa83 100644
--- a/browser/base/content/browser.js
+++ b/browser/base/content/browser.js
@@ -1021,7 +1021,7 @@ function handleUriInChrome(aBrowser, aUri) {
 
 // A shared function used by both remote and non-remote browser XBL bindings to
 // load a URI or redirect it to the correct process.
-function _loadURIWithFlags(browser, uri, params) {
+function _loadURI(browser, uri, params = {}) {
   let tab = gBrowser.getTabForBrowser(browser);
   // Preloaded browsers don't have tabs, so we ignore those.
   if (tab) {
@@ -1031,12 +1031,15 @@ function _loadURIWithFlags(browser, uri, params) {
   if (!uri) {
     uri = "about:blank";
   }
-  let triggeringPrincipal = params.triggeringPrincipal || null;
-  let flags = params.flags || 0;
-  let referrer = params.referrerURI;
-  let referrerPolicy = ("referrerPolicy" in params ? params.referrerPolicy :
-                        Ci.nsIHttpChannel.REFERRER_POLICY_UNSET);
-  let postData = params.postData;
+
+  let {
+    flags = Ci.nsIWebNavigation.LOAD_FLAGS_NONE,
+    referrerURI,
+    referrerPolicy = Ci.nsIHttpChannel.REFERRER_POLICY_UNSET,
+    triggeringPrincipal,
+    postData,
+    userContextId,
+  } = params || {};
 
   let currentRemoteType = browser.remoteType;
   let requiredRemoteType;
@@ -1082,12 +1085,12 @@ function _loadURIWithFlags(browser, uri, params) {
   }
   try {
     if (!mustChangeProcess) {
-      if (params.userContextId) {
-        browser.webNavigation.setOriginAttributesBeforeLoading({ userContextId: params.userContextId });
+      if (userContextId) {
+        browser.webNavigation.setOriginAttributesBeforeLoading({ userContextId });
       }
 
       browser.webNavigation.loadURIWithOptions(uri, flags,
-                                               referrer, referrerPolicy,
+                                               referrerURI, referrerPolicy,
                                                postData, null, null, triggeringPrincipal);
     } else {
       // Check if the current browser is allowed to unload.
@@ -1106,15 +1109,15 @@ function _loadURIWithFlags(browser, uri, params) {
           ? gSerializationHelper.serializeToString(triggeringPrincipal)
           : null,
         flags,
-        referrer: referrer ? referrer.spec : null,
+        referrer: referrerURI ? referrerURI.spec : null,
         referrerPolicy,
         remoteType: requiredRemoteType,
         postData,
         newFrameloader,
       };
 
-      if (params.userContextId) {
-        loadParams.userContextId = params.userContextId;
+      if (userContextId) {
+        loadParams.userContextId = userContextId;
       }
 
       LoadInOtherProcess(browser, loadParams);
@@ -1129,11 +1132,11 @@ function _loadURIWithFlags(browser, uri, params) {
       Cu.reportError(e);
       gBrowser.updateBrowserRemotenessByURL(browser, uri);
 
-      if (params.userContextId) {
-        browser.webNavigation.setOriginAttributesBeforeLoading({ userContextId: params.userContextId });
+      if (userContextId) {
+        browser.webNavigation.setOriginAttributesBeforeLoading({ userContextId: userContextId });
       }
 
-      browser.webNavigation.loadURIWithOptions(uri, flags, referrer, referrerPolicy,
+      browser.webNavigation.loadURIWithOptions(uri, flags, referrerURI, referrerPolicy,
                                                postData, null, null, triggeringPrincipal);
     } else {
       throw e;
@@ -3171,7 +3174,7 @@ var BrowserOnClick = {
     // Allow users to override and continue through to the site,
     // but add a notify bar as a reminder, so that they don't lose
     // track after, e.g., tab switching.
-    gBrowser.loadURIWithFlags(gBrowser.currentURI.spec, {
+    gBrowser.loadURI(gBrowser.currentURI.spec, {
       flags: Ci.nsIWebNavigation.LOAD_FLAGS_BYPASS_CLASSIFIER,
     });
 
@@ -3296,13 +3299,13 @@ function BrowserReloadWithFlags(reloadFlags) {
     // If the remoteness has changed, the new browser doesn't have any
     // information of what was loaded before, so we need to load the previous
     // URL again.
-    gBrowser.loadURIWithFlags(url, { flags: reloadFlags });
+    gBrowser.loadURI(url, { flags: reloadFlags });
     return;
   }
 
   // Do this after the above case where we might flip remoteness.
   // Unfortunately, we'll count the remoteness flip case as a
-  // "newURL" load, since we're using loadURIWithFlags, but hopefully
+  // "newURL" load, since we're using loadURI, but hopefully
   // that's rare enough to not matter.
   maybeRecordAbandonmentTelemetry(gBrowser.selectedTab, "reload");
 
@@ -5340,7 +5343,7 @@ nsBrowserAccess.prototype = {
           let loadflags = isExternal ?
                             Ci.nsIWebNavigation.LOAD_FLAGS_FROM_EXTERNAL :
                             Ci.nsIWebNavigation.LOAD_FLAGS_NONE;
-          gBrowser.loadURIWithFlags(aURI.spec, {
+          gBrowser.loadURI(aURI.spec, {
             triggeringPrincipal: aTriggeringPrincipal,
             flags: loadflags,
             referrerURI: referrer,
diff --git a/browser/base/content/tabbrowser.js b/browser/base/content/tabbrowser.js
index 4651995c52bc..a6efb9e7ee6f 100644
--- a/browser/base/content/tabbrowser.js
+++ b/browser/base/content/tabbrowser.js
@@ -120,7 +120,7 @@ window._gBrowser = {
    */
   _browserBindingProperties: [
     "canGoBack", "canGoForward", "goBack", "goForward", "permitUnload",
-    "reload", "reloadWithFlags", "stop", "loadURI", "loadURIWithFlags",
+    "reload", "reloadWithFlags", "stop", "loadURI",
     "gotoIndex", "currentURI", "documentURI",
     "preferences", "imageDocument", "isRemoteBrowser", "messageManager",
     "getTabBrowser", "finder", "fastFind", "sessionHistory", "contentTitle",
@@ -346,15 +346,8 @@ window._gBrowser = {
   /**
    * throws exception for unknown schemes
    */
-  loadURI(aURI, aReferrerURI, aCharset) {
-    return this.selectedBrowser.loadURI(aURI, aReferrerURI, aCharset);
-  },
-
-  /**
-   * throws exception for unknown schemes
-   */
-  loadURIWithFlags(aURI, aParams) {
-    return this.mCurrentBrowser.loadURIWithFlags(aURI, aParams);
+  loadURI(aURI, aParams) {
+    return this.selectedBrowser.loadURI(aURI, aParams);
   },
 
   gotoIndex(aIndex) {
@@ -1493,7 +1486,7 @@ window._gBrowser = {
           Ci.nsIWebNavigation.LOAD_FLAGS_FIXUP_SCHEME_TYPOS;
       }
       try {
-        browser.loadURIWithFlags(aURIs[0], {
+        browser.loadURI(aURIs[0], {
           flags,
           postData: aPostDatas[0],
           triggeringPrincipal: aTriggeringPrincipal,
@@ -2426,7 +2419,7 @@ window._gBrowser = {
       if (aDisallowInheritPrincipal)
         flags |= Ci.nsIWebNavigation.LOAD_FLAGS_DISALLOW_INHERIT_PRINCIPAL;
       try {
-        b.loadURIWithFlags(aURI, {
+        b.loadURI(aURI, {
           flags,
           triggeringPrincipal: aTriggeringPrincipal,
           referrerURI: aNoReferrer ? null : aReferrerURI,
diff --git a/browser/base/content/tabbrowser.xml b/browser/base/content/tabbrowser.xml
index 68dd7e0f5cee..2f332891cdcf 100644
--- a/browser/base/content/tabbrowser.xml
+++ b/browser/base/content/tabbrowser.xml
@@ -2311,12 +2311,12 @@
       <field name="tabModalPromptBox">null</field>
 
       <!-- throws exception for unknown schemes -->
-      <method name="loadURIWithFlags">
+      <method name="loadURI">
         <parameter name="aURI"/>
         <parameter name="aParams"/>
         <body>
           <![CDATA[
-            _loadURIWithFlags(this, aURI, aParams);
+            _loadURI(this, aURI, aParams);
           ]]>
         </body>
       </method>
@@ -2329,12 +2329,12 @@
       <field name="tabModalPromptBox">null</field>
 
       <!-- throws exception for unknown schemes -->
-      <method name="loadURIWithFlags">
+      <method name="loadURI">
         <parameter name="aURI"/>
         <parameter name="aParams"/>
         <body>
           <![CDATA[
-            _loadURIWithFlags(this, aURI, aParams);
+            _loadURI(this, aURI, aParams);
           ]]>
         </body>
       </method>
diff --git a/browser/base/content/test/general/browser_e10s_switchbrowser.js b/browser/base/content/test/general/browser_e10s_switchbrowser.js
index 58fe0be72134..b119a92774e5 100644
--- a/browser/base/content/test/general/browser_e10s_switchbrowser.js
+++ b/browser/base/content/test/general/browser_e10s_switchbrowser.js
@@ -77,7 +77,7 @@ var waitForLoad = async function(uri) {
 // Waits for a load and updates the known history
 var waitForLoadWithFlags = async function(uri, flags = Ci.nsIWebNavigation.LOAD_FLAGS_NONE) {
   info("Loading " + uri + " flags = " + flags);
-  gBrowser.selectedBrowser.loadURIWithFlags(uri, { flags });
+  gBrowser.selectedBrowser.loadURI(uri, { flags });
 
   await BrowserTestUtils.browserStopped(gBrowser);
   if (!(flags & Ci.nsIWebNavigation.LOAD_FLAGS_BYPASS_HISTORY)) {
diff --git a/browser/base/content/utilityOverlay.js b/browser/base/content/utilityOverlay.js
index 0b59f1fc7bff..fd4f5b5dc018 100644
--- a/browser/base/content/utilityOverlay.js
+++ b/browser/base/content/utilityOverlay.js
@@ -448,7 +448,7 @@ function openLinkIn(url, where, params) {
       targetBrowser.createAboutBlankContentViewer(aPrincipal);
     }
 
-    targetBrowser.loadURIWithFlags(url, {
+    targetBrowser.loadURI(url, {
       triggeringPrincipal: aTriggeringPrincipal,
       flags,
       referrerURI: aNoReferrer ? null : aReferrerURI,
diff --git a/browser/base/content/webext-panels.js b/browser/base/content/webext-panels.js
index 087ce80237cb..2e97a3942719 100644
--- a/browser/base/content/webext-panels.js
+++ b/browser/base/content/webext-panels.js
@@ -108,6 +108,6 @@ function loadPanel(extensionId, extensionUrl, browserStyle) {
   getBrowser(sidebar).then(browser => {
     let uri = Services.io.newURI(policy.getURL());
     let triggeringPrincipal = Services.scriptSecurityManager.createCodebasePrincipal(uri, {});
-    browser.loadURIWithFlags(extensionUrl, {triggeringPrincipal});
+    browser.loadURI(extensionUrl, {triggeringPrincipal});
   });
 }
diff --git a/browser/components/extensions/ExtensionPopups.jsm b/browser/components/extensions/ExtensionPopups.jsm
index dd9ce9f48ed2..22696f1c3da8 100644
--- a/browser/components/extensions/ExtensionPopups.jsm
+++ b/browser/components/extensions/ExtensionPopups.jsm
@@ -316,7 +316,7 @@ class BasePopup {
         stylesheets: this.STYLESHEETS,
       });
 
-      browser.loadURIWithFlags(popupURL, {triggeringPrincipal: this.extension.principal});
+      browser.loadURI(popupURL, {triggeringPrincipal: this.extension.principal});
     });
   }
 
diff --git a/browser/components/extensions/ext-devtools-panels.js b/browser/components/extensions/ext-devtools-panels.js
index 09f2486619b3..bfb7929b8f32 100644
--- a/browser/components/extensions/ext-devtools-panels.js
+++ b/browser/components/extensions/ext-devtools-panels.js
@@ -278,7 +278,7 @@ class ParentDevToolsPanel {
       },
     });
 
-    browser.loadURIWithFlags(url, {
+    browser.loadURI(url, {
       triggeringPrincipal: extension.principal,
     });
   }
diff --git a/browser/components/extensions/ext-devtools.js b/browser/components/extensions/ext-devtools.js
index f6ab2f86c1e4..376f82a608e7 100644
--- a/browser/components/extensions/ext-devtools.js
+++ b/browser/components/extensions/ext-devtools.js
@@ -176,7 +176,7 @@ class DevToolsPage extends HiddenExtensionPage {
       },
     });
 
-    this.browser.loadURIWithFlags(this.url, {
+    this.browser.loadURI(this.url, {
       triggeringPrincipal: this.extension.principal,
     });
 
diff --git a/browser/components/extensions/ext-tabs.js b/browser/components/extensions/ext-tabs.js
index cde15f296e2d..f70398a5d206 100644
--- a/browser/components/extensions/ext-tabs.js
+++ b/browser/components/extensions/ext-tabs.js
@@ -614,7 +614,7 @@ this.tabs = class extends ExtensionAPI {
                       : Ci.nsIWebNavigation.LOAD_FLAGS_NONE,
               triggeringPrincipal: context.principal,
             };
-            nativeTab.linkedBrowser.loadURIWithFlags(url, options);
+            nativeTab.linkedBrowser.loadURI(url, options);
           }
 
           if (updateProperties.active !== null) {
diff --git a/browser/components/extensions/ext-url-overrides.js b/browser/components/extensions/ext-url-overrides.js
index 3eb6d87808b6..160c4386c064 100644
--- a/browser/components/extensions/ext-url-overrides.js
+++ b/browser/components/extensions/ext-url-overrides.js
@@ -58,7 +58,7 @@ function replaceUrlInTab(gBrowser, tab, url) {
       },
     });
   });
-  gBrowser.loadURIWithFlags(url, {
+  gBrowser.loadURI(url, {
     flags: Ci.nsIWebNavigation.LOAD_FLAGS_REPLACE_HISTORY,
   });
   return loaded;
diff --git a/browser/components/search/test/browser_aboutSearchReset.js b/browser/components/search/test/browser_aboutSearchReset.js
index 14abe4617ed7..9202b9c729b1 100644
--- a/browser/components/search/test/browser_aboutSearchReset.js
+++ b/browser/components/search/test/browser_aboutSearchReset.js
@@ -33,10 +33,10 @@ function checkTelemetryRecords(expectedValue) {
 function promiseStoppedLoad(expectedURL) {
   return new Promise(resolve => {
     let browser = gBrowser.selectedBrowser;
-    let original = browser.loadURIWithFlags;
-    browser.loadURIWithFlags = function(URI) {
+    let original = browser.loadURI;
+    browser.loadURI = function(URI) {
       if (URI == expectedURL) {
-        browser.loadURIWithFlags = original;
+        browser.loadURI = original;
         ok(true, "loaded expected url: " + URI);
         resolve();
         return;
diff --git a/browser/components/sessionstore/SessionStore.jsm b/browser/components/sessionstore/SessionStore.jsm
index 8d974cb83e28..ed8b594989a4 100644
--- a/browser/components/sessionstore/SessionStore.jsm
+++ b/browser/components/sessionstore/SessionStore.jsm
@@ -2901,7 +2901,7 @@ var SessionStoreInternal = {
     // a flash of the about:tabcrashed page after selecting
     // the revived tab.
     aTab.removeAttribute("crashed");
-    browser.loadURI("about:blank", null, null);
+    browser.loadURI("about:blank");
 
     let data = TabState.collect(aTab);
     this.restoreTab(aTab, data, {
diff --git a/browser/components/sessionstore/test/browser_491168.js b/browser/components/sessionstore/test/browser_491168.js
index 18258efebb4c..43641c612e31 100644
--- a/browser/components/sessionstore/test/browser_491168.js
+++ b/browser/components/sessionstore/test/browser_491168.js
@@ -17,7 +17,7 @@ add_task(async function() {
 
   // Load a new URI with a specific referrer.
   let referrerURI = Services.io.newURI(REFERRER1);
-  browser.loadURI("http://example.org", referrerURI, null);
+  browser.loadURI("http://example.org", { referrerURI });
   await promiseBrowserLoaded(browser);
 
   await TabStateFlusher.flush(browser);
diff --git a/browser/components/sessionstore/test/browser_closed_objects_changed_notifications_tabs.js b/browser/components/sessionstore/test/browser_closed_objects_changed_notifications_tabs.js
index f380f7200d24..9cc1a6056c13 100644
--- a/browser/components/sessionstore/test/browser_closed_objects_changed_notifications_tabs.js
+++ b/browser/components/sessionstore/test/browser_closed_objects_changed_notifications_tabs.js
@@ -12,7 +12,7 @@ let notificationsCount = 0;
 async function openWindow(url) {
   let win = await promiseNewWindowLoaded();
   let flags = Ci.nsIWebNavigation.LOAD_FLAGS_REPLACE_HISTORY;
-  win.gBrowser.selectedBrowser.loadURIWithFlags(url, { flags });
+  win.gBrowser.selectedBrowser.loadURI(url, { flags });
   await promiseBrowserLoaded(win.gBrowser.selectedBrowser, true, url);
   return win;
 }
diff --git a/browser/components/sessionstore/test/browser_closed_objects_changed_notifications_windows.js b/browser/components/sessionstore/test/browser_closed_objects_changed_notifications_windows.js
index e07bf8ff770c..e9ea6132c98a 100644
--- a/browser/components/sessionstore/test/browser_closed_objects_changed_notifications_windows.js
+++ b/browser/components/sessionstore/test/browser_closed_objects_changed_notifications_windows.js
@@ -14,7 +14,7 @@ let notificationsCount = 0;
 async function openWindow(url) {
   let win = await promiseNewWindowLoaded();
   let flags = Ci.nsIWebNavigation.LOAD_FLAGS_REPLACE_HISTORY;
-  win.gBrowser.selectedBrowser.loadURIWithFlags(url, { flags });
+  win.gBrowser.selectedBrowser.loadURI(url, { flags });
   await promiseBrowserLoaded(win.gBrowser.selectedBrowser, true, url);
   return win;
 }
diff --git a/browser/components/sessionstore/test/browser_dying_cache.js b/browser/components/sessionstore/test/browser_dying_cache.js
index 1910e7b7b581..e5eb8d18aaa4 100644
--- a/browser/components/sessionstore/test/browser_dying_cache.js
+++ b/browser/components/sessionstore/test/browser_dying_cache.js
@@ -12,7 +12,7 @@ add_task(async function test() {
 
   // Load some URL in the current tab.
   let flags = Ci.nsIWebNavigation.LOAD_FLAGS_REPLACE_HISTORY;
-  win.gBrowser.selectedBrowser.loadURIWithFlags("about:robots", { flags });
+  win.gBrowser.selectedBrowser.loadURI("about:robots", { flags });
   await promiseBrowserLoaded(win.gBrowser.selectedBrowser);
 
   // Open a second tab and close the first one.
diff --git a/browser/components/sessionstore/test/browser_undoCloseById.js b/browser/components/sessionstore/test/browser_undoCloseById.js
index 6c98465534bb..c0deec9b7420 100644
--- a/browser/components/sessionstore/test/browser_undoCloseById.js
+++ b/browser/components/sessionstore/test/browser_undoCloseById.js
@@ -17,7 +17,7 @@ async function openAndCloseTab(window, url) {
 async function openWindow(url) {
   let win = await promiseNewWindowLoaded();
   let flags = Ci.nsIWebNavigation.LOAD_FLAGS_REPLACE_HISTORY;
-  win.gBrowser.selectedBrowser.loadURIWithFlags(url, { flags });
+  win.gBrowser.selectedBrowser.loadURI(url, { flags });
   await promiseBrowserLoaded(win.gBrowser.selectedBrowser, true, url);
   return win;
 }
diff --git a/browser/modules/ContentSearch.jsm b/browser/modules/ContentSearch.jsm
index 58dcdffef4bd..7a59b71f3a28 100644
--- a/browser/modules/ContentSearch.jsm
+++ b/browser/modules/ContentSearch.jsm
@@ -239,8 +239,7 @@ var ContentSearch = {
       // Since we're going to load the search in the same browser, blur the search
       // UI to prevent further interaction before we start loading.
       this._reply(msg, "Blur");
-      browser.loadURIWithFlags(submission.uri.spec, {
-        flags: Ci.nsIWebNavigation.LOAD_FLAGS_NONE,
+      browser.loadURI(submission.uri.spec, {
         postData: submission.postData
       });
     } else {
diff --git a/devtools/client/netmonitor/test/browser_net_frame.js b/devtools/client/netmonitor/test/browser_net_frame.js
index a0d4db9f16d0..b9f297a06562 100644
--- a/devtools/client/netmonitor/test/browser_net_frame.js
+++ b/devtools/client/netmonitor/test/browser_net_frame.js
@@ -167,7 +167,7 @@ add_task(async function() {
 
   store.dispatch(Actions.batchEnable(false));
 
-  tab.linkedBrowser.loadURI(TOP_URL, null, null);
+  tab.linkedBrowser.loadURI(TOP_URL);
 
   await waitForNetworkEvents(monitor, REQUEST_COUNT);
 
diff --git a/devtools/client/responsive.html/browser/swap.js b/devtools/client/responsive.html/browser/swap.js
index 5d66a47c8bef..ba78a0a18467 100644
--- a/devtools/client/responsive.html/browser/swap.js
+++ b/devtools/client/responsive.html/browser/swap.js
@@ -124,7 +124,7 @@ function swapToInnerBrowser({ tab, containerURL, getInnerBrowser }) {
       });
       // Prevent the `containerURL` from ending up in the tab's history.
       debug("Load container URL");
-      containerBrowser.loadURIWithFlags(containerURL, {
+      containerBrowser.loadURI(containerURL, {
         flags: Ci.nsIWebNavigation.LOAD_FLAGS_BYPASS_HISTORY,
       });
 
diff --git a/devtools/client/responsive.html/test/browser/head.js b/devtools/client/responsive.html/test/browser/head.js
index d405c27d38b3..183e126fdb52 100644
--- a/devtools/client/responsive.html/test/browser/head.js
+++ b/devtools/client/responsive.html/test/browser/head.js
@@ -315,7 +315,7 @@ function waitForViewportLoad(ui) {
 
 function load(browser, url) {
   let loaded = BrowserTestUtils.browserLoaded(browser, false, url);
-  browser.loadURI(url, null, null);
+  browser.loadURI(url);
   return loaded;
 }
 
diff --git a/docshell/test/browser/browser_loadDisallowInherit.js b/docshell/test/browser/browser_loadDisallowInherit.js
index b00b0632ebc9..63e34c558ffc 100644
--- a/docshell/test/browser/browser_loadDisallowInherit.js
+++ b/docshell/test/browser/browser_loadDisallowInherit.js
@@ -22,7 +22,7 @@ function startTest() {
     BrowserTestUtils.browserLoaded(browser, false, url).then(() => {
       func();
     });
-    browser.loadURIWithFlags(url, { flags });
+    browser.loadURI(url, { flags });
   }
 
   // Load a normal http URL
diff --git a/docshell/test/browser/browser_loadURI.js b/docshell/test/browser/browser_loadURI.js
index 567fb1664aaf..d0601dd62f6c 100644
--- a/docshell/test/browser/browser_loadURI.js
+++ b/docshell/test/browser/browser_loadURI.js
@@ -20,8 +20,7 @@ function test() {
   postStream.addHeader("Content-Type", "application/x-www-form-urlencoded");
   postStream.setData(dataStream);
 
-  tab.linkedBrowser.loadURIWithFlags("http://mochi.test:8888/browser/docshell/test/browser/print_postdata.sjs", {
-    flags: 0,
+  tab.linkedBrowser.loadURI("http://mochi.test:8888/browser/docshell/test/browser/print_postdata.sjs", {
     postData: postStream,
   });
   BrowserTestUtils.browserLoaded(tab.linkedBrowser).then(() => {
diff --git a/mobile/android/chrome/content/browser.js b/mobile/android/chrome/content/browser.js
index fd8231245946..9eeafb22ce8e 100644
--- a/mobile/android/chrome/content/browser.js
+++ b/mobile/android/chrome/content/browser.js
@@ -1172,7 +1172,7 @@ var BrowserApp = {
     }
 
     try {
-      aBrowser.loadURIWithFlags(aURI, {
+      aBrowser.loadURI(aURI, {
         flags,
         referrerURI,
         charset,
@@ -3497,7 +3497,7 @@ nsBrowserAccess.prototype = {
       }
 
       let openerWindow = (aFlags & Ci.nsIBrowserDOMWindow.OPEN_NO_OPENER) ? null : aOpener;
-      // BrowserApp.addTab calls loadURIWithFlags with the appropriate params
+      // BrowserApp.addTab calls loadURI with the appropriate params
       let tab = BrowserApp.addTab(aURI ? aURI.spec : "about:blank", { flags: loadflags,
                                                                       referrerURI: referrer,
                                                                       external: isExternal,
@@ -3514,7 +3514,7 @@ nsBrowserAccess.prototype = {
     // OPEN_CURRENTWINDOW and illegal values
     let browser = BrowserApp.selectedBrowser;
     if (aURI && browser) {
-      browser.loadURIWithFlags(aURI.spec, {
+      browser.loadURI(aURI.spec, {
         flags: loadflags,
         referrerURI: referrer,
         triggeringPrincipal: aTriggeringPrincipal,
@@ -3780,7 +3780,7 @@ Tab.prototype = {
       this.isSearch = "isSearch" in aParams ? aParams.isSearch : false;
 
       try {
-        this.browser.loadURIWithFlags(aURL, {
+        this.browser.loadURI(aURL, {
           flags,
           referrerURI,
           charset,
diff --git a/mobile/android/modules/geckoview/GeckoViewNavigation.jsm b/mobile/android/modules/geckoview/GeckoViewNavigation.jsm
index f29259faf47b..2e6c3169dfd2 100644
--- a/mobile/android/modules/geckoview/GeckoViewNavigation.jsm
+++ b/mobile/android/modules/geckoview/GeckoViewNavigation.jsm
@@ -75,7 +75,7 @@ class GeckoViewNavigation extends GeckoViewModule {
           navFlags |= Ci.nsIWebNavigation.LOAD_FLAGS_ALLOW_POPUPS;
         }
 
-        this.browser.loadURIWithFlags(uri, {
+        this.browser.loadURI(uri, {
           flags: navFlags,
           referrerURI: referrer,
         });
diff --git a/testing/talos/talos/pageloader/chrome/pageloader.js b/testing/talos/talos/pageloader/chrome/pageloader.js
index 15ac69e4aca3..563e43ccb61b 100644
--- a/testing/talos/talos/pageloader/chrome/pageloader.js
+++ b/testing/talos/talos/pageloader/chrome/pageloader.js
@@ -321,7 +321,7 @@ function startAndLoadURI(pageName) {
 
   start_time = Date.now();
   if (loadNoCache) {
-    content.loadURIWithFlags(pageName, {
+    content.loadURI(pageName, {
       flags: Ci.nsIWebNavigation.LOAD_FLAGS_BYPASS_CACHE
     });
   } else {
diff --git a/toolkit/components/extensions/ext-backgroundPage.js b/toolkit/components/extensions/ext-backgroundPage.js
index 626270d60e23..808056ea15da 100644
--- a/toolkit/components/extensions/ext-backgroundPage.js
+++ b/toolkit/components/extensions/ext-backgroundPage.js
@@ -31,7 +31,7 @@ class BackgroundPage extends HiddenExtensionPage {
 
     extensions.emit("extension-browser-inserted", this.browser);
 
-    this.browser.loadURIWithFlags(this.url, {triggeringPrincipal: this.extension.principal});
+    this.browser.loadURI(this.url, {triggeringPrincipal: this.extension.principal});
 
     let context = await promiseExtensionViewLoaded(this.browser);
     TelemetryStopwatch.finish("WEBEXT_BACKGROUND_PAGE_LOAD_MS", this);
diff --git a/toolkit/content/widgets/browser.xml b/toolkit/content/widgets/browser.xml
index 2aa5b5c8040e..e39d45a4dba3 100644
--- a/toolkit/content/widgets/browser.xml
+++ b/toolkit/content/widgets/browser.xml
@@ -102,24 +102,6 @@
 
       <!-- throws exception for unknown schemes -->
       <method name="loadURI">
-        <parameter name="aURI"/>
-        <parameter name="aReferrerURI"/>
-        <parameter name="aCharset"/>
-        <body>
-          <![CDATA[
-            this._wrapURIChangeCall(() =>
-              this.loadURIWithFlags(aURI, {
-                flags: Ci.nsIWebNavigation.LOAD_FLAGS_NONE,
-                referrerURI: aReferrerURI,
-                charset: aCharset,
-              })
-            );
-          ]]>
-        </body>
-      </method>
-
-      <!-- throws exception for unknown schemes -->
-      <method name="loadURIWithFlags">
         <parameter name="aURI"/>
         <parameter name="aParams"/>
         <body>
@@ -129,12 +111,12 @@
             }
 
             let {
-              flags,
+              flags = Ci.nsIWebNavigation.LOAD_FLAGS_NONE,
               referrerURI,
               referrerPolicy = Ci.nsIHttpChannel.REFERRER_POLICY_UNSET,
               triggeringPrincipal,
               postData,
-            } = aParams;
+            } = aParams || {};
 
             this._wrapURIChangeCall(() =>
               this.webNavigation.loadURIWithOptions(
diff --git a/toolkit/mozapps/extensions/content/extensions.js b/toolkit/mozapps/extensions/content/extensions.js
index 08d32b88fdaa..dcef548998b6 100644
--- a/toolkit/mozapps/extensions/content/extensions.js
+++ b/toolkit/mozapps/extensions/content/extensions.js
@@ -2220,7 +2220,7 @@ var gDiscoverView = {
     if (!aKeepHistory)
       flags |= Ci.nsIWebNavigation.LOAD_FLAGS_REPLACE_HISTORY;
 
-    this._browser.loadURIWithFlags(aURL, { flags });
+    this._browser.loadURI(aURL, { flags });
   },
 
   onLocationChange(aWebProgress, aRequest, aLocation, aFlags) {
diff --git a/widget/tests/test_bug428405.xul b/widget/tests/test_bug428405.xul
index 1d164fecb42c..6d8578a97edf 100644
--- a/widget/tests/test_bug428405.xul
+++ b/widget/tests/test_bug428405.xul
@@ -56,7 +56,7 @@
     // 6) Start reloading first tab.
     function loadFirstTab() {
       var browser = document.getElementById("tab1browser");
-      browser.loadURI("data:text/html;charset=utf-8,<body><h2>First Tab</h2><p><input type='submit' value='Button' id='button1'/></body>", null, null);
+      browser.loadURI("data:text/html;charset=utf-8,<body><h2>First Tab</h2><p><input type='submit' value='Button' id='button1'/></body>");
     }
 
     function configureFirstTab() {
@@ -81,7 +81,7 @@
     // 8) Start loading second tab.
     function loadSecondTab() {
       var browser = document.getElementById("tab2browser");
-      browser.loadURI("data:text/html;charset=utf-8,<body><h2>Second Tab</h2><p><input type='submit' value='Button' id='button1'/></body>", null, null);
+      browser.loadURI("data:text/html;charset=utf-8,<body><h2>Second Tab</h2><p><input type='submit' value='Button' id='button1'/></body>");
     }
 
     function configureSecondTab() {