--- admin/plib/modules/panel-migrator/backend/lib/python/parallels/core/utils/http_client.py.orig
+++ admin/plib/modules/panel-migrator/backend/lib/python/parallels/core/utils/http_client.py
@@ -98,6 +98,10 @@ def perform_http_request_response(url, data=None, headers=None, hostname=None, i
     """
     headers = default(headers, {})
 
+    if 'User-Agent' not in headers:
+        # specify user agent to avoid requests rejection by web server
+        headers['User-Agent'] = 'Mozilla/5.0 (Windows NT 6.3; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/54.0.2840.71 Safari/537.36'
+
     # General algorithm for "old" Python
     if (sys.version_info.major, sys.version_info.minor, sys.version_info.micro) < (2, 7, 9):
         https_handler = HTTPSHandler(ip_address=ip_address)