diff --git a/clearml/backend_config/defs.py b/clearml/backend_config/defs.py
index 22efcb60..02bbc841 100644
--- a/clearml/backend_config/defs.py
+++ b/clearml/backend_config/defs.py
@@ -59,7 +59,7 @@ def is_config_file(path):
 
 def get_active_config_file():
     f = LOCAL_CONFIG_FILE_OVERRIDE_VAR.get()
-    if exists(expanduser(expandvars(f))):
+    if f and exists(expanduser(expandvars(f))):
         return f
     for f in LOCAL_CONFIG_FILES:
         if exists(expanduser(expandvars(f))):