{"id":5147,"date":"2026-08-30T08:20:35","date_gmt":"2026-08-29T23:20:35","guid":{"rendered":"https:\/\/donguri3.net\/server-tech\/gsc-sitemap-not-updating-fix-2\/"},"modified":"2026-08-30T08:20:36","modified_gmt":"2026-08-29T23:20:36","slug":"gsc-sitemap-not-updating-fix","status":"publish","type":"post","link":"https:\/\/donguri3.net\/en\/server-tech\/wordpress-blog-seo\/gsc-sitemap-not-updating-fix\/","title":{"rendered":"How to Fix Unupdated Sitemaps in Google Search Console: Improving with Last-Modified and 304 Responses"},"content":{"rendered":"

An issue occurred where the sitemap fetch date was not updating in Google Search Console (hereafter GSC), preventing new articles from being reflected in the index.
The site is operated on a WordPress + OpenLiteSpeed (LiteSpeed Cache plugin) environment. While the parent sitemap (sitemap.xml<\/code>) was being fetched, monthly child sitemaps (e.g., sitemap-posttype-post.202508.xml<\/code>) had not been updated since August 5th.<\/p>\n

Since Bing Webmaster Tools was retrieving them normally, I deduced that the conditions related to Google’s crawling decisions and update detection were not being met.<\/p>\n

\n

Objective<\/h2>\n
    \n
  • \n

    Ensure GSC reliably detects updates to child sitemaps<\/p>\n<\/li>\n

  • \n

    Keep the sitemap fetch date updated and promote the indexing of new pages<\/p>\n<\/li>\n

  • \n

    Prevent future erroneous caching and missed update detections<\/p>\n<\/li>\n<\/ul>\n

    \n

    Issues Identified Through Investigation<\/h2>\n
    $ curl -I https:\/\/donguri3.net\/sitemap-posttype-post.202508.xml\nHTTP\/2 200\netag: "1924cd0be2d2a478d9675f0d7d647bd6"\ncontent-type: application\/xml; charset=UTF-8\nx-robots-tag: noindex, follow\nexpires: Wed, 11 Jan 1984 05:00:00 GMT\ncache-control: no-cache, must-revalidate, max-age=0, no-store, private, no-store\nlink: &amp;lt;https:\/\/donguri3.net\/wp-json\/&amp;gt;; rel="https:\/\/api.w.org\/"\nvary: Accept-Encoding\nx-litespeed-cache: hit\ndate: Sun, 10 Aug 2025 13:40:14 GMT\nserver: LiteSpeed\nalt-svc: h3=":443"; ma=2592000, h3-29=":443"; ma=2592000, h3-Q050=":443"; ma=2592000, h3-Q046=":443"; ma=2592000, h3-Q043=":443"; ma=2592000, quic=":443"; ma=2592000; v="43,46"<\/pre>\n
      \n
    1. \n
      Missing Last-Modified<\/code> Header<\/strong><\/p>\n
        \n
      • \n
        Google uses Last-Modified<\/code> as a reference for update detection, but it was not included in WordPress’s output.<\/p>\n<\/li>\n<\/ul>\n<\/li>\n
      • \n
        Potential ETag Fixation<\/strong><\/p>\n
          \n
        • \n
          Due to LiteSpeed caching and plugin effects, ETags may not change even when the content changes.<\/p>\n<\/li>\n<\/ul>\n<\/li>\n
        • \n
          Sitemaps Subject to LiteSpeed Cache<\/strong><\/p>\n
            \n
          • \n
            There was a risk that older XML would be returned due to cache hits.<\/p>\n<\/li>\n<\/ul>\n<\/li>\n
          • \n
            Lack of Support for If-Modified-Since<\/strong><\/p>\n
              \n
            • \n
              Even when Googlebot sends conditional requests, it returns 200 every time instead of 304 Not Modified.
              \u2192 Results in wasteful re-fetches, leading to inefficient crawling.<\/p>\n<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n
              \n
              Solutions<\/h2>\n
              1. Exclude Sitemaps from Caching<\/h3>\n
              In LiteSpeed Cache (LSCWP), go to Cache > Exclude and add the following to “Do Not Cache URIs”.<\/p>\n
              \/sitemap.xml\n\/sitemap-*.xml\n\/sitemap-posttype-*.xml\n\/*sitemap*.xml<\/pre>\n
              <\/div>\n
              Additionally, added bypass rules to .htaccess<\/code> or the OLS VHost Rewrite so that enabling caching in the future will not affect them.<\/p>\n
              # --- Completely bypass Sitemaps (prevent future erroneous caching) ---\nRewriteCond %{REQUEST_URI} "(^\/sitemap\\.xml$|\/sitemap-.*\\.xml$|\/.*sitemap.*\\.xml$)"\nRewriteRule .* - [E=cache-control:no-cache,E=cache-disable=1]<\/pre>\n
              \n
              2. Implementing Last-Modified<\/code> and 304 Responses<\/h3>\n
              In functions.php<\/code>, retrieve the last modified timestamp from the actual child sitemap data (the latest updated article of that month) and set it to Last-Modified<\/code>.
              Furthermore, compare it with If-Modified-Since<\/code>, and if it is identical or newer, return 304 Not Modified<\/strong>.<\/p>\n
              \nadd_action('init', function () {\n$req = $_SERVER['REQUEST_URI'] ?? '';\nif (!preg_match('#\/(wp-sitemap|sitemap).*\\.xml$#', $req)) return;\n\n$lm_ts = null;\nif (preg_match('#\/sitemap-posttype-post\\.(\\d{4})(\\d{2})\\.xml$#', $req, $m)) {\n$q = new WP_Query([\n'post_type' =&gt; 'post',\n'post_status' =&gt; 'publish',\n'date_query' =&gt; [['year' =&gt; (int)$m[1], 'month' =&gt; (int)$m[2]]],\n'orderby' =&gt; 'modified',\n'order' =&gt; 'DESC',\n'posts_per_page' =&gt; 1,\n'no_found_rows' =&gt; true,\n'fields' =&gt; 'ids',\n]);\nif (!is_wp_error($q) &amp;&amp; !empty($q-&gt;posts)) {\n$lm_ts = (int) get_post_modified_time('U', true, $q-&gt;posts[0]);\n}\nwp_reset_postdata();\n}\nif (!$lm_ts) $lm_ts = time() - 600;\n\n$lm_http = gmdate('D, d M Y H:i:s', $lm_ts) . ' GMT';\nheader_remove('ETag');\nheader('Last-Modified: ' . $lm_http, true);\nheader('Cache-Control: no-cache, must-revalidate, max-age=0, no-store, private', true);\n\n$ims_raw = $_SERVER['HTTP_IF_MODIFIED_SINCE'] ?? '';\n$ims_ts = $ims_raw ? strtotime($ims_raw) : false;\n\nif ($ims_ts !== false &amp;&amp; $ims_ts &gt;= $lm_ts) {\nstatus_header(304);\nhttp_response_code(304);\nif (php_sapi_name() === 'cgi-fcgi') header('Status: 304 Not Modified', true);\nheader('Content-Length: 0');\nexit;\n}\n}, 0);<\/pre>\n
              \n
              3. Operation Verification<\/h3>\n
              Header Check<\/h4>\n
              curl -I https:\/\/blog.example.com\/sitemap-posttype-post.202508.xml<\/pre>\n
                \n
              • \n
                Last-Modified<\/code> matches the actual last modification time<\/p>\n<\/li>\n
              • \n
                No ETag<\/code><\/p>\n<\/li>\n
              • \n
                Cache-Control<\/code> set to no-cache<\/p>\n<\/li>\n<\/ul>\n
                304 Response Check<\/h4>\n
                LM="Sat, 02 Aug 2025 06:05:23 GMT"\ncurl -I -H "If-Modified-Since: $LM" https:\/\/blog.example.com\/sitemap-posttype-post.202508.xml<\/pre>\n
                \u2192 HTTP\/2 304 Not Modified<\/code><\/p>\n
                \n
                Results<\/h2>\n
                After the fix, I resubmitted<\/strong> the child sitemap whose fetching had stalled in GSC. After a short while, it displayed as “Success,” and the last fetch date was updated.
                Subsequently, new articles have been smoothly indexed as well.<\/p>\n
                \n
                Summary<\/h2>\n
                  \n
                • \n
                  The Last-Modified<\/code> header is crucial for update detection<\/strong><\/p>\n<\/li>\n
                • \n
                  Cache exclusion settings are mandatory<\/strong> (especially in LiteSpeed environments)<\/p>\n<\/li>\n
                • \n
                  304 responses reduce wasteful crawls and improve update detection accuracy<\/strong><\/p>\n<\/li>\n
                • \n
                  When the “Last read” date in GSC does not update, review both server and application caching and header settings<\/p>\n<\/li>\n<\/ul>\n
                  With this response, Google’s crawling stabilized, and indexing speed improved.
                  If you are facing a similar issue where sitemaps are not updating in GSC, be sure to check your Last-Modified<\/code> and cache control settings.<\/p>\n","protected":false},"excerpt":{"rendered":"
                  An issue occurred where the sitemap fetch date was not updating in Google Search Console (hereafter GSC), prev […]<\/p>\n","protected":false},"author":4,"featured_media":1952,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_locale":"en_US","_original_post":"https:\/\/donguri3.net\/?p=1950","footnotes":""},"categories":[1166],"tags":[193,52,15,13,14,196,61,10,194],"class_list":["post-5147","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-wordpress-blog-seo","tag-google-search-console","tag-https","tag-litespeed","tag-ols","tag-openlitespeed","tag-seo","tag-wordpress","tag-server","tag-194","en-US"],"_links":{"self":[{"href":"https:\/\/donguri3.net\/wp-json\/wp\/v2\/posts\/5147","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/donguri3.net\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/donguri3.net\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/donguri3.net\/wp-json\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/donguri3.net\/wp-json\/wp\/v2\/comments?post=5147"}],"version-history":[{"count":1,"href":"https:\/\/donguri3.net\/wp-json\/wp\/v2\/posts\/5147\/revisions"}],"predecessor-version":[{"id":5150,"href":"https:\/\/donguri3.net\/wp-json\/wp\/v2\/posts\/5147\/revisions\/5150"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/donguri3.net\/wp-json\/wp\/v2\/media\/1952"}],"wp:attachment":[{"href":"https:\/\/donguri3.net\/wp-json\/wp\/v2\/media?parent=5147"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/donguri3.net\/wp-json\/wp\/v2\/categories?post=5147"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/donguri3.net\/wp-json\/wp\/v2\/tags?post=5147"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}