diff --git a/RAP4/customizations/bootstrap/files/ExecEngineFunctions.php b/RAP4/customizations/bootstrap/files/ExecEngineFunctions.php
index d7d51e0e..8c0eceef 100644
--- a/RAP4/customizations/bootstrap/files/ExecEngineFunctions.php
+++ b/RAP4/customizations/bootstrap/files/ExecEngineFunctions.php
@@ -343,13 +343,7 @@
     $zipContentForCommandline = base64_encode($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;
+    $userName = sanitize_username($userName);
 
     $deployment = getenv('RAP_DEPLOYMENT');
     if ($deployment == 'Kubernetes') {
@@ -477,6 +471,33 @@
     $scriptVersionAtom->link($message, 'compileresponse[ScriptVersion*CompileResponse]')->add();
 });
 
+/**Sanitize the username
+ * As the user is allowed to choose any name, it is possible that the name they chose does not conform to restrictions places on the string in certain use cases.
+ * For example, a user could use special characters in their username. This might violate the restrictions placed on strings in a kubernetes metadata.name field.
+ * Therefore we remove all characters deemed unfit, and create a hash from these characters and append this hash at the end.
+ * To prevent casting errors between int and string, we append 'st' at the beginning.
+*/
+function sanitize_username($username) {
+    // Define the pattern of illegal characters
+    $pattern = '/[^a-zA-Z0-9]/';
+
+    // Find all illegal characters
+    preg_match_all($pattern, $username, $matches);
+
+    // Remove illegal characters
+    $sanitized_username = preg_replace($pattern, '', $username);
+
+    // Create a hash of the illegal characters
+    $hash = !empty($matches[0]) ? substr(md5(implode($matches[0])), 0, 5) : '';
+
+    // Append the hash to the sanitized username
+    $sanitized_username .= $hash;
+
+    $sanitized_username = 'st' . $sanitized_username;
+
+    return strtolower($sanitized_username);
+}
+
 /**
  * @phan-closure-scope \Ampersand\Rule\ExecEngine
  * Phan analyzes the inner body of this closure as if it were a closure declared in ExecEngine.