diff --git a/extensions/browser/process_manager.cc b/extensions/browser/process_manager.cc
index 2e412026f5e74..e19424740e022 100644
--- a/extensions/browser/process_manager.cc
+++ b/extensions/browser/process_manager.cc
@@ -876,22 +876,33 @@ void ProcessManager::CloseLazyBackgroundPageNow(const ExtensionId& extension_id,
       return;
     }
 
-    // Close remaining views.
-    std::vector<content::RenderFrameHost*> frames_to_close;
+    // Close remaining views. WebContents::ClosePage() can synchronously
+    // destroy the tab (and every RenderFrameHost in it) when the tab's main
+    // frame is already ready to be closed -- e.g. while a JavaScript dialog
+    // is showing -- so collect frame IDs rather than bare pointers and re-
+    // resolve on each iteration to avoid dereferencing a freed RFH.
+    std::vector<content::GlobalRenderFrameHostId> frames_to_close;
     for (const auto& key_value : all_extension_frames_) {
       if (key_value.second.CanKeepalive() &&
           GetExtensionID(key_value.first) == extension_id) {
         DCHECK(!key_value.second.has_keepalive);
-        frames_to_close.push_back(key_value.first);
+        frames_to_close.push_back(key_value.first->GetGlobalId());
       }
     }
-    for (content::RenderFrameHost* frame : frames_to_close) {
+    for (const content::GlobalRenderFrameHostId& frame_id : frames_to_close) {
+      content::RenderFrameHost* frame =
+          content::RenderFrameHost::FromID(frame_id);
+      if (!frame) {
+        continue;
+      }
       content::WebContents::FromRenderFrameHost(frame)->ClosePage();
       // WebContents::ClosePage() may result in calling
       // UnregisterRenderFrameHost() asynchronously and may cause race
       // conditions when the background page is reloaded.
       // To avoid this, unregister the view now.
-      UnregisterRenderFrameHost(frame);
+      if (content::RenderFrameHost::FromID(frame_id)) {
+        UnregisterRenderFrameHost(frame);
+      }
     }
 
     host = GetBackgroundHostForExtension(extension_id);