diff --git a/admin/webservice/forms.php b/admin/webservice/forms.php
index 4f15173f35c..4f5d837c380 100644
--- a/admin/webservice/forms.php
+++ b/admin/webservice/forms.php
@@ -196,8 +196,12 @@ class external_service_functions_form extends moodleform {
         //we add the descriptions to the functions
         foreach ($functions as $functionid => $functionname) {
             //retrieve full function information (including the description)
-            $function = \core_external\external_api::external_function_info($functionname);
-            if (empty($function->deprecated)) {
+            try {
+                $function = \core_external\external_api::external_function_info($functionname);
+            } catch (Throwable $exception) {
+                $function = null;
+            }
+            if ($function !== null && empty($function->deprecated)) {
                 $functions[$functionid] = $function->name . ':' . $function->description;
             } else {
                 // Exclude the deprecated ones.