diff --git a/addons/web/static/src/core/browser/router_service.js b/addons/web/static/src/core/browser/router_service.js
index 9b722e9d839..b29f6078c58 100644
--- a/addons/web/static/src/core/browser/router_service.js
+++ b/addons/web/static/src/core/browser/router_service.js
@@ -110,8 +110,8 @@ async function redirect(env, url, wait = false) {
     browser.location.assign(url);
 }
 
-function getRoute() {
-    const { pathname, search, hash } = browser.location;
+function getRoute(urlObj) {
+    const { pathname, search, hash } = urlObj;
     const searchQuery = parseSearchQuery(search);
     const hashQuery = parseHash(hash);
     return { pathname, search: searchQuery, hash: hashQuery };
@@ -120,10 +120,12 @@ function getRoute() {
 function makeRouter(env) {
     const bus = env.bus;
     const lockedKeys = new Set();
-    let current = getRoute();
+    let current = getRoute(browser.location);
     let pushTimeout;
-    browser.addEventListener("hashchange", () => {
-        current = getRoute();
+    browser.addEventListener("hashchange", (ev) => {
+        browser.clearTimeout(pushTimeout);
+        const loc = new URL(ev.newURL);
+        current = getRoute(loc);
         bus.trigger("ROUTE_CHANGE");
     });
 
@@ -155,7 +157,7 @@ function makeRouter(env) {
             } else {
                 browser.history.replaceState({}, "", url);
             }
-            current = getRoute();
+            current = getRoute(browser.location);
         }
         return function pushOrReplaceState(hash, options) {
             allPushArgs.push([hash, options]);
diff --git a/addons/web/static/tests/setup.js b/addons/web/static/tests/setup.js
index 8f8fa75a6c8..4d69924bcfe 100644
--- a/addons/web/static/tests/setup.js
+++ b/addons/web/static/tests/setup.js
@@ -58,7 +58,7 @@ function forceLocaleAndTimezoneWithCleanup() {
     });
 }
 
-function makeMockLocation() {
+function makeMockLocation(hasListeners = () => true) {
     const locationLink = Object.assign(document.createElement("a"), {
         href: window.location.origin + window.location.pathname,
         assign(url) {
@@ -71,10 +71,22 @@ function makeMockLocation() {
             return target[p];
         },
         set(target, p, value) {
-            target[p] = value;
             if (p === "hash") {
-                window.dispatchEvent(new HashChangeEvent("hashchange"));
+                const oldURL = new URL(locationLink.href).toString();
+                target[p] = value;
+                const newURL = new URL(locationLink.href).toString();
+
+                if (!hasListeners()) {
+                    return true;
+                }
+                // the event hashchange must be triggered in a nonBlocking stack
+                // https://html.spec.whatwg.org/multipage/browsing-the-web.html#scroll-to-fragid
+                window.setTimeout(() => {
+                    window.dispatchEvent(new HashChangeEvent("hashchange", { oldURL, newURL }));
+                });
+                return true;
             }
+            target[p] = value;
             return true;
         },
     });
@@ -83,13 +95,18 @@ function makeMockLocation() {
 function patchBrowserWithCleanup() {
     const originalAddEventListener = browser.addEventListener;
     const originalRemoveEventListener = browser.removeEventListener;
-    const mockLocation = makeMockLocation();
+
+    let hasHashChangeListeners = false;
+    const mockLocation = makeMockLocation(() => hasHashChangeListeners);
     patchWithCleanup(
         browser,
         {
             // patch addEventListner to automatically remove listeners bound (via
             // browser.addEventListener) during a test (e.g. during the deployment of a service)
-            addEventListener() {
+            addEventListener(evName) {
+                if (evName === "hashchange") {
+                    hasHashChangeListeners = true;
+                }
                 originalAddEventListener(...arguments);
                 registerCleanup(() => {
                     originalRemoveEventListener(...arguments);
diff --git a/addons/web/static/tests/webclient/actions/load_state_tests.js b/addons/web/static/tests/webclient/actions/load_state_tests.js
index a1f007f5c57..f20a847ed84 100644
--- a/addons/web/static/tests/webclient/actions/load_state_tests.js
+++ b/addons/web/static/tests/webclient/actions/load_state_tests.js
@@ -8,7 +8,7 @@ import core from "web.core";
 import AbstractAction from "web.AbstractAction";
 import { registerCleanup } from "../../helpers/cleanup";
 import { makeTestEnv } from "../../helpers/mock_env";
-import { click, getFixture, legacyExtraNextTick, patchWithCleanup } from "../../helpers/utils";
+import { click, getFixture, legacyExtraNextTick, patchWithCleanup, nextTick } from "../../helpers/utils";
 import {
     createWebClient,
     doAction,
@@ -966,4 +966,62 @@ QUnit.module("ActionManager", (hooks) => {
             menu_id: 1,
         });
     });
+
+    QUnit.test("concurrent hashchange during action mounting -- 1", async (assert) => {
+        assert.expect(5);
+
+        class MyAction extends Component {
+            mounted() {
+                browser.location.hash = "#action=__test__client__action__&menu_id=1";
+            }
+        }
+        MyAction.template = tags.xml`<div class="not-here" />`;
+        registry.category("actions").add("myAction", MyAction);
+
+        browser.location.hash = "#action=myAction";
+
+        const webClient = await createWebClient({ serverData });
+        assert.containsOnce(webClient, ".not-here");
+        assert.containsNone(webClient, ".test_client_action");
+
+        await nextTick();
+        assert.containsNone(webClient, ".not-here");
+        assert.containsOnce(webClient, ".test_client_action");
+
+        assert.deepEqual(webClient.env.services.router.current.hash, {
+            action: "__test__client__action__",
+            menu_id: 1,
+        });
+    });
+
+    QUnit.test("concurrent hashchange during action mounting -- 2", async (assert) => {
+        assert.expect(5);
+
+        const baseURL = new URL(browser.location.href).toString();
+
+        class MyAction extends Component {
+            mounted() {
+                const newURL = baseURL + "#action=__test__client__action__&menu_id=1";
+                // immediate triggering
+                window.dispatchEvent(new HashChangeEvent("hashchange", { newURL }));
+            }
+        }
+        MyAction.template = tags.xml`<div class="not-here" />`;
+        registry.category("actions").add("myAction", MyAction);
+
+        browser.location.hash = "#action=myAction";
+        const webClient = await createWebClient({ serverData });
+
+        assert.containsOnce(webClient, ".not-here");
+        assert.containsNone(webClient, ".test_client_action");
+
+        await nextTick();
+        assert.containsNone(webClient, ".not-here");
+        assert.containsOnce(webClient, ".test_client_action");
+
+        assert.deepEqual(webClient.env.services.router.current.hash, {
+            action: "__test__client__action__",
+            menu_id: 1,
+        });
+    });
 });
diff --git a/addons/web/static/tests/webclient/helpers.js b/addons/web/static/tests/webclient/helpers.js
index 58272c21e04..b192cee6b45 100644
--- a/addons/web/static/tests/webclient/helpers.js
+++ b/addons/web/static/tests/webclient/helpers.js
@@ -279,7 +279,12 @@ export async function loadState(env, state) {
         env = env.env;
     }
     env.bus.trigger("test:hashchange", state);
+    // wait the asynchronous hashchange
+    // (the event hashchange must be triggered in a nonBlocking stack)
     await nextTick();
+    // wait for the regular rendering
+    await nextTick();
+    // wait for the legacy rendering below owl layer
     await legacyExtraNextTick();
 }