Fix NotFoundSetOnFormSubmit_ResponseNotStarted_SSR test and enhanced navigation timing issue

src/Components/Web.JS/src/Boot.Web.ts

@@ -65,13 +65,13 @@ function boot(options?: Partial<WebStartOptions>) : Promise<void> {
     },
   };
 
-  attachComponentDescriptorHandler(rootComponentManager);
-  attachStreamingRenderingListener(options?.ssr, navigationEnhancementCallbacks);
-
   if (!options?.ssr?.disableDomPreservation) {
     attachProgressivelyEnhancedNavigationListener(navigationEnhancementCallbacks);
   }
 
+  attachComponentDescriptorHandler(rootComponentManager);
+  attachStreamingRenderingListener(options?.ssr, navigationEnhancementCallbacks);
+
   enableFocusOnNavigate(jsEventRegistry);
 
   // Wait until the initial page response completes before activating interactive components.

src/Components/Web.JS/src/Services/NavigationEnhancement.ts

@@ -37,11 +37,18 @@ const acceptHeader = 'text/html; blazor-enhanced-nav=on';
 let currentEnhancedNavigationAbortController: AbortController | null;
 let navigationEnhancementCallbacks: NavigationEnhancementCallbacks;
 let performingEnhancedPageLoad: boolean;
+let navigationEnhancementCallbacksPromise: Promise<NavigationEnhancementCallbacks> | null = null;
+let navigationEnhancementCallbacksResolver: ((callbacks: NavigationEnhancementCallbacks) => void) | null = null;
 
 // This gets initialized to the current URL when we load.
 // After that, it gets updated every time we successfully complete a navigation.
 let currentContentUrl = location.href;
 
+// Initialize the promise for waiting for navigation enhancement callbacks
+navigationEnhancementCallbacksPromise = new Promise<NavigationEnhancementCallbacks>((resolve) => {
+  navigationEnhancementCallbacksResolver = resolve;
+});
+
 export interface NavigationEnhancementCallbacks {
   enhancedNavigationStarted: () => void;
   documentUpdated: () => void;
@@ -58,6 +65,14 @@ export function hasNeverStartedAnyEnhancedPageLoad() {
 
 export function attachProgressivelyEnhancedNavigationListener(callbacks: NavigationEnhancementCallbacks) {
   navigationEnhancementCallbacks = callbacks;
+
+  // Resolve the promise so any waiting performEnhancedPageLoad calls can proceed
+  if (navigationEnhancementCallbacksResolver) {
+    navigationEnhancementCallbacksResolver(callbacks);
+    navigationEnhancementCallbacksResolver = null;
+    navigationEnhancementCallbacksPromise = null;
+  }
+
   document.addEventListener('click', onDocumentClick);
   document.addEventListener('submit', onDocumentSubmit);
   window.addEventListener('popstate', onPopState);
@@ -195,6 +210,10 @@ function onDocumentSubmit(event: SubmitEvent) {
 export async function performEnhancedPageLoad(internalDestinationHref: string, interceptedLink: boolean, fetchOptions?: RequestInit, treatAsRedirectionFromMethod?: 'get' | 'post', changeUrl: boolean = true) {
   performingEnhancedPageLoad = true;
 
+  if (!navigationEnhancementCallbacks && navigationEnhancementCallbacksPromise) {
+    navigationEnhancementCallbacks = await navigationEnhancementCallbacksPromise;
+  }
+
   // First, stop any preceding enhanced page load
   currentEnhancedNavigationAbortController?.abort();
 

src/Components/test/E2ETest/ServerRenderingTests/NoInteractivityTest.cs

@@ -205,7 +205,7 @@ private void AssertNotFoundRendered_ResponseStarted_Or_POST(bool hasReExecutionM
     public void NotFoundSetOnFormSubmit_ResponseNotStarted_SSR(bool hasReExecutionMiddleware, bool hasCustomNotFoundPageSet)
     {
         string reexecution = hasReExecutionMiddleware ? "/reexecution" : "";
-        string testUrl = $"{ServerPathBase}{reexecution}/post-not-found-ssr-streaming?useCustomNotFoundPage={hasCustomNotFoundPageSet}";
+        string testUrl = $"{ServerPathBase}{reexecution}/post-not-found-ssr?useCustomNotFoundPage={hasCustomNotFoundPageSet}";
         Navigate(testUrl);
         Browser.FindElement(By.Id("not-found-form")).FindElement(By.TagName("button")).Click();