diff --git a/src/app/document/controllers/DocumentController.php b/src/app/document/controllers/DocumentController.php
index fb523bbee90e0a9e4ab0da1f627449736c84ced4..8d9dd43b7986a2e719948526ff59786ac15849a4 100644
--- a/src/app/document/controllers/DocumentController.php
+++ b/src/app/document/controllers/DocumentController.php
@@ -493,7 +493,7 @@ class DocumentController
             if ($hasElectronicSignature && $workflow['signatureMode'] == 'stamp' && $workflow['mode'] == 'sign') {
                 return $response->withStatus(400)->withJson(['errors' => "Body workflow[{$key}] signatureMode cannot be stamp after an electronic signature", 'lang' => 'stampInTheMiddleImpossible']);
             }
-            if ($workflow['externalInformations']['role'] ?? null == 'otp_sign_yousign' && empty($workflow['signaturePositions'])) {
+            if (($workflow['externalInformations']['role'] ?? null) == 'otp_sign_yousign' && empty($workflow['signaturePositions'])) {
                 return $response->withStatus(400)->withJson(['errors' => "Body workflow[{$key}] signaturePositions must be set for sign_yousign role"]);
             }
             if (!empty($workflow['signaturePositions'])) {
@@ -1240,7 +1240,7 @@ class DocumentController
             return $response->withStatus(400)->withJson(['errors' => 'Docserver does not exist']);
         }
 
-        $pathToThumbnail = $docserver['path'] . $adr[0]['path'] . $adr[0]['filename'];
+        $pathToThumbnail = $docserver['path'] . $adr[0]['path'] ?? null . $adr[0]['filename'] ?? null;
         if (!is_file($pathToThumbnail) || !is_readable($pathToThumbnail)) {
             $configPath = CoreConfigModel::getConfigPath();
             exec("php src/app/convert/scripts/ThumbnailScript.php '{$configPath}' {$args['id']} 'document' '{$GLOBALS['id']}' {$args['page']} > /dev/null");
@@ -1588,7 +1588,7 @@ class DocumentController
                         $signHeight = null;
                     } else {
                         $signWidth  = ($signature['width'] * $size['width']) / 100;
-                        $signHeight = ($signature['height'] * $size['height']) / 100;
+                        $signHeight = ($signature['height'] ?? null * $size['height'])/ 100;
                         $signPosX   = ($signature['positionX'] * $size['width']) / 100;
                         $signPosY   = ($signature['positionY'] * $size['height']) / 100;
                     }