diff --git a/admin/webservice/documentation.php b/admin/webservice/documentation.php
index 9ccca8b14eb..265ec883d6c 100644
--- a/admin/webservice/documentation.php
+++ b/admin/webservice/documentation.php
@@ -29,13 +29,6 @@ require_once($CFG->dirroot . '/webservice/lib.php');
 
 admin_externalpage_setup('webservicedocumentation');
 
-// get all the function descriptions
-$functions = $DB->get_records('external_functions', array(), 'name');
-$functiondescs = array();
-foreach ($functions as $function) {
-    $functiondescs[$function->name] = external_api::external_function_info($function);
-}
-
 // TODO: MDL-76078 - Incorrect inter-communication, core cannot have plugin dependencies like this.
 
 //display the documentation for all documented protocols,
@@ -50,6 +43,19 @@ $printableformat = optional_param('print', false, PARAM_BOOL);
 /// OUTPUT
 echo $OUTPUT->header();
 
+// Get all the function descriptions.
+$functions = $DB->get_records('external_functions', [], 'name');
+$functiondescs = [];
+foreach ($functions as $function) {
+
+    // Skip invalid or otherwise incorrectly defined functions, otherwise the entire page is rendered inaccessible.
+    try {
+        $functiondescs[$function->name] = external_api::external_function_info($function);
+    } catch (Throwable $exception) {
+        echo $OUTPUT->notification($exception->getMessage(), \core\output\notification::NOTIFY_ERROR);
+    }
+}
+
 $renderer = $PAGE->get_renderer('core', 'webservice');
 echo $renderer->documentation_html($functiondescs,
         $printableformat, $protocols, array(), $PAGE->url);
diff --git a/lib/externallib.php b/lib/externallib.php
index 666b49940cf..551b329ba18 100644
--- a/lib/externallib.php
+++ b/lib/externallib.php
@@ -64,6 +64,7 @@ class external_api {
      * @param int $strictness IGNORE_MISSING means compatible mode, false returned if record not found, debug message if more found;
      *                        MUST_EXIST means throw exception if no record or multiple records found
      * @return stdClass description or false if not found or exception thrown
+     * @throws coding_exception for any property and/or method that is missing or invalid
      * @since Moodle 2.0
      */
     public static function external_function_info($function, $strictness=MUST_EXIST) {