diff --git a/RAP4/customizations/bootstrap/files/ExecEngineFunctions.php b/RAP4/customizations/bootstrap/files/ExecEngineFunctions.php
index 6857eb2b..d7d51e0e 100644
--- a/RAP4/customizations/bootstrap/files/ExecEngineFunctions.php
+++ b/RAP4/customizations/bootstrap/files/ExecEngineFunctions.php
@@ -343,11 +343,14 @@
     $zipContentForCommandline = base64_encode($zipContent);
     $mainAldForCommandLine = base64_encode("main.adl");
 
+    //sanitize the username for usage later
     $pattern = '/[\W+]/';
 
     $userName=strtolower($userName);
     $userName = preg_replace($pattern, '-', $userName);
 
+    $userName = 'st-' . $userName;
+
     $deployment = getenv('RAP_DEPLOYMENT');
     if ($deployment == 'Kubernetes') {
         /** Deployed on Kubernetes Cluster