diff --git a/admin/category.php b/admin/category.php
index 31df0629136..e11507a218a 100644
--- a/admin/category.php
+++ b/admin/category.php
@@ -48,6 +48,12 @@ if (!($settingspage->check_access())) {
     print_error('accessdenied', 'admin');
 }
 
+$hassiteconfig = has_capability('moodle/site:config', $PAGE->context);
+if ($hassiteconfig) {
+    $PAGE->add_header_action($OUTPUT->render_from_template('core_admin/header_search_input', [
+        'action' => new moodle_url('/admin/search.php'),
+    ]));
+}
 
 $statusmsg = '';
 $errormsg  = '';
diff --git a/admin/search.php b/admin/search.php
index c225d72cb69..2d1920d5ec1 100644
--- a/admin/search.php
+++ b/admin/search.php
@@ -28,18 +28,6 @@ if ($hassiteconfig && moodle_needs_upgrading()) {
 admin_externalpage_setup('search', '', array('query' => $query)); // now hidden page
 $PAGE->set_heading(get_string('administrationsite')); // Has to be after setup since it has its' own heading set_heading.
 
-if ($hassiteconfig) {
-    $data = [
-        'action' => new moodle_url('/admin/search.php'),
-        'btnclass' => 'btn-primary',
-        'inputname' => 'query',
-        'searchstring' => get_string('search'),
-        'query' => $query,
-        'extraclasses' => 'd-flex justify-content-end'
-    ];
-    $PAGE->add_header_action($OUTPUT->render_from_template('core/search_input', $data));
-}
-
 $adminroot = admin_get_root(); // need all settings here
 $adminroot->search = $query; // So we can reference it in search boxes later in this invocation
 $statusmsg = '';
diff --git a/admin/settings.php b/admin/settings.php
index 1df90252c54..7adbac3ac2f 100644
--- a/admin/settings.php
+++ b/admin/settings.php
@@ -33,6 +33,13 @@ if (!($settingspage->check_access())) {
     die;
 }
 
+$hassiteconfig = has_capability('moodle/site:config', $PAGE->context);
+if ($hassiteconfig) {
+    $PAGE->add_header_action($OUTPUT->render_from_template('core_admin/header_search_input', [
+        'action' => new moodle_url('/admin/search.php'),
+    ]));
+}
+
 /// WRITING SUBMITTED DATA (IF ANY) -------------------------------------------------------------------------------
 
 $statusmsg = '';
diff --git a/admin/templates/header_search_input.mustache b/admin/templates/header_search_input.mustache
new file mode 100644
index 00000000000..51a6386f105
--- /dev/null
+++ b/admin/templates/header_search_input.mustache
@@ -0,0 +1,52 @@
+{{!
+    This file is part of Moodle - http://moodle.org/
+
+    Moodle is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    Moodle is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+}}
+{{!
+    @template core_admin/header_search_input
+
+    Admin search input for page header.
+
+    Example context (json):
+    {
+        "action": "http://moodle.local/admin/search.php",
+        "query": "themedesigner"
+    }
+}}
+<div class="simplesearchform d-flex justify-content-end">
+  <form autocomplete="off" action="{{action}}" method="get" accept-charset="utf-8" class="mform form-inline simplesearchform">
+    <div class="input-group">
+      <label for="searchinput-{{uniqid}}">
+        <span class="sr-only">{{#str}} search, core {{/str}}</span>
+      </label>
+      <input type="text"
+             id="searchinput-{{uniqid}}"
+             class="form-control"
+             placeholder="{{#str}} search, core {{/str}}"
+             aria-label="{{#str}} search, core {{/str}}"
+             name="query"
+             data-region="input"
+             autocomplete="off"
+             {{#query}}value="{{.}}"{{/query}}
+      >
+      <div class="input-group-append">
+        <button type="submit" class="btn btn-primary search-icon">
+          {{#pix}} a/search, core {{/pix}}
+          <span class="sr-only">{{#str}} search, core {{/str}}</span>
+        </button>
+      </div>
+    </div>
+  </form>
+</div>
diff --git a/lib/adminlib.php b/lib/adminlib.php
index fdc812747e7..65c04420d3d 100644
--- a/lib/adminlib.php
+++ b/lib/adminlib.php
@@ -8804,10 +8804,11 @@ function admin_externalpage_setup($section, $extrabutton = '', array $extraurlpa
     $adminroot = admin_get_root(false, false); // settings not required for external pages
     $extpage = $adminroot->locate($section, true);
 
+    $hassiteconfig = has_capability('moodle/site:config', context_system::instance());
     if (empty($extpage) or !($extpage instanceof admin_externalpage)) {
         // The requested section isn't in the admin tree
         // It could be because the user has inadequate capapbilities or because the section doesn't exist
-        if (!has_capability('moodle/site:config', context_system::instance())) {
+        if (!$hassiteconfig) {
             // The requested section could depend on a different capability
             // but most likely the user has inadequate capabilities
             print_error('accessdenied', 'admin');
@@ -8878,6 +8879,13 @@ function admin_externalpage_setup($section, $extrabutton = '', array $extraurlpa
     $PAGE->set_title("$SITE->shortname: " . implode(": ", $visiblepathtosection));
     $PAGE->set_heading($SITE->fullname);
 
+    if ($hassiteconfig) {
+        $PAGE->add_header_action($OUTPUT->render_from_template('core_admin/header_search_input', [
+            'action' => new moodle_url('/admin/search.php'),
+            'query' => $PAGE->url->get_param('query'),
+        ]));
+    }
+
     // prevent caching in nav block
     $PAGE->navigation->clear_cache();
 }