diff --git a/mod/lti/OAuth.php b/mod/lti/OAuth.php
index 6dd60f0bec0..0790c4c5dca 100644
--- a/mod/lti/OAuth.php
+++ b/mod/lti/OAuth.php
@@ -445,10 +445,15 @@ class OAuthRequest {
     }
 
     /**
-     * parses the url and rebuilds it to be
-     * scheme://host/path
+     * Parses {@see http_url} and returns normalized scheme://host/path if non-empty, otherwise return empty string
+     *
+     * @return string
      */
     public function get_normalized_http_url() {
+        if ($this->http_url === '') {
+            return '';
+        }
+
         $parts = parse_url($this->http_url);
 
         $port = @$parts['port'];
diff --git a/mod/lti/locallib.php b/mod/lti/locallib.php
index 36c61262e09..7668e676631 100644
--- a/mod/lti/locallib.php
+++ b/mod/lti/locallib.php
@@ -593,11 +593,11 @@ function lti_get_launch_data($instance, $nonce = '') {
             $endpoint = trim($instance->securetoolurl);
         }
 
-        $endpoint = lti_ensure_url_is_https($endpoint);
-    } else {
-        if (!strstr($endpoint, '://')) {
-            $endpoint = 'http://' . $endpoint;
+        if ($endpoint !== '') {
+            $endpoint = lti_ensure_url_is_https($endpoint);
         }
+    } else if ($endpoint !== '' && !strstr($endpoint, '://')) {
+        $endpoint = 'http://' . $endpoint;
     }
 
     $orgid = lti_get_organizationid($typeconfig);
@@ -3455,7 +3455,8 @@ function lti_post_launch_html($newparms, $endpoint, $debug=false) {
     }
     $r .= "</form>\n";
 
-    if ( ! $debug ) {
+    // Auto-submit the form if endpoint is set.
+    if ($endpoint !== '' && !$debug) {
         $r .= " <script type=\"text/javascript\"> \n" .
             "  //<![CDATA[ \n" .
             "    document.ltiLaunchForm.submit(); \n" .