From 8b0f01fa9baca8c762ae0e3525a7f58063c9c097 Mon Sep 17 00:00:00 2001
From: Veloman Yunkan <veloman.yunkan@gmail.com>
Date: Thu, 27 Nov 2025 17:55:14 +0400
Subject: [PATCH] Fix for intermittent /content/blank.html errors

Monitoring of the iframe content URL could result in the check being
performed while the iframe placeholder page /skin/blank.html was still
loaded (a slow connection increased the odds of it happening). This was
contrary to the assumptions behind the logic of that procedure and the
outcome was an attempt to load the /content/blank.html page with a
subsequent 404 error.

Now that situation is taken into account.
---
 static/skin/viewer.js | 6 ++++--
 test/server.cpp       | 4 ++--
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/static/skin/viewer.js b/static/skin/viewer.js
index c683158c..0b0ee719 100644
--- a/static/skin/viewer.js
+++ b/static/skin/viewer.js
@@ -271,10 +271,12 @@ function translateErrorPageIfNeeded() {
 let iframeLocationHref = null;
 
 function handle_content_url_change() {
-  if ( iframeLocationHref == contentIframe.contentWindow.location.href )
+  const iframeLocation = contentIframe.contentWindow.location;
+
+  if ( iframeLocationHref == iframeLocation.href ||
+       !iframeLocation.pathname.startsWith(root + '/content/') )
     return;
 
-  const iframeLocation = contentIframe.contentWindow.location;
   iframeLocationHref = iframeLocation.href;
   console.log('handle_content_url_change: ' + iframeLocation.href);
   document.title = contentIframe.contentDocument.title;
diff --git a/test/server.cpp b/test/server.cpp
index a9c766c5..61e90a98 100644
--- a/test/server.cpp
+++ b/test/server.cpp
@@ -77,7 +77,7 @@ const ResourceCollection resources200Compressible{
   { DYNAMIC_CONTENT, "/ROOT%23%3F/skin/taskbar.css" },
   { STATIC_CONTENT,  "/ROOT%23%3F/skin/taskbar.css?cacheid=42e90cb9" },
   { DYNAMIC_CONTENT, "/ROOT%23%3F/skin/viewer.js" },
-  { STATIC_CONTENT,  "/ROOT%23%3F/skin/viewer.js?cacheid=3208c3ed" },
+  { STATIC_CONTENT,  "/ROOT%23%3F/skin/viewer.js?cacheid=914d363c" },
   { DYNAMIC_CONTENT, "/ROOT%23%3F/skin/fonts/Poppins.ttf" },
   { STATIC_CONTENT,  "/ROOT%23%3F/skin/fonts/Poppins.ttf?cacheid=af705837" },
   { DYNAMIC_CONTENT, "/ROOT%23%3F/skin/fonts/Roboto.ttf" },
@@ -338,7 +338,7 @@ R"EXPECTEDRESULT(    <link type="text/css" href="./skin/kiwix.css?cacheid=b4e29e
     <script type="text/javascript" src="./skin/polyfills.js?cacheid=a0e0343d"></script>
     <script type="module" src="./skin/i18n.js?cacheid=e9a10ac1" defer></script>
     <script type="text/javascript" src="./skin/languages.js?cacheid=08955948" defer></script>
-    <script type="text/javascript" src="./skin/viewer.js?cacheid=3208c3ed" defer></script>
+    <script type="text/javascript" src="./skin/viewer.js?cacheid=914d363c" defer></script>
     <script type="text/javascript" src="./skin/autoComplete/autoComplete.min.js?cacheid=1191aaaf"></script>
       const blankPageUrl = root + "/skin/blank.html?cacheid=6b1fa032";
           <label for="kiwix_button_show_toggle"><img src="./skin/caret.png?cacheid=22b942b4" alt=""></label>