Fix navigation for hash routers on manual URL changes (#9980)

Author: brophdawg11

.changeset/six-tigers-fold.md

@@ -0,0 +1,6 @@
+---
+"react-router-dom": patch
+"@remix-run/router": patch
+---
+
+Fix navigation for hash routers on manual URL changes

packages/router/history.ts

@@ -85,7 +85,7 @@ export interface Update {
   /**
    * The delta between this location and the former location in the history stack
    */
-  delta: number;
+  delta: number | null;
 }
 
 /**
@@ -612,24 +612,12 @@ function getUrlBasedHistory(
   }
 
   function handlePop() {
-    let nextAction = Action.Pop;
+    action = Action.Pop;
     let nextIndex = getIndex();
-
-    if (nextIndex != null) {
-      let delta = nextIndex - index;
-      action = nextAction;
-      index = nextIndex;
-      if (listener) {
-        listener({ action, location: history.location, delta });
-      }
-    } else {
-      warning(
-        false,
-        `You are trying to perform a POP navigation to a location that was not ` +
-          `created by @remix-run/router. This will fail silently in production.  ` +
-          `You should navigate via the router to avoid this situation (instead of ` +
-          `using window.history.pushState/window.location.hash).`
-      );
+    let delta = nextIndex == null ? null : nextIndex - index;
+    index = nextIndex;
+    if (listener) {
+      listener({ action, location: history.location, delta });
     }
   }
 

packages/router/router.ts

@@ -781,12 +781,23 @@ export function createRouter(init: RouterInit): Router {
           return;
         }
 
+        warning(
+          activeBlocker != null && delta === null,
+          "You are trying to use a blocker on a POP navigation to a location " +
+            "that was not created by @remix-run/router. This will fail silently in " +
+            "production. This can happen if you are navigating outside the router " +
+            "via `window.history.pushState`/`window.location.hash` instead of using " +
+            "router navigation APIs.  This can also happen if you are using " +
+            "createHashRouter and the user manually changes the URL."
+        );
+
         let blockerKey = shouldBlockNavigation({
           currentLocation: state.location,
           nextLocation: location,
           historyAction,
         });
-        if (blockerKey) {
+
+        if (blockerKey && delta != null) {
           // Restore the URL to match the current UI, but don't update router state
           ignoreNextHistoryUpdate = true;
           init.history.go(delta * -1);