diff --git a/src/caosdb/configuration.py b/src/caosdb/configuration.py
index 90abc91637968bb589304a7b7da9d3ebb33fdf8b..314a1a1d0eb25091333c7b5528e32512a3679d96 100644
--- a/src/caosdb/configuration.py
+++ b/src/caosdb/configuration.py
@@ -24,6 +24,7 @@
 
 import os
 import yaml
+import warnings
 try:
     optional_jsonschema_validate = None
     from jsonschema import validate as optional_jsonschema_validate
@@ -87,6 +88,10 @@ def validate_yaml_schema(valobj):
         with open(os.path.join(os.path.dirname(__file__), "schema-pycaosdb-ini.yml")) as f:
             schema = yaml.load(f, Loader=yaml.SafeLoader)
         optional_jsonschema_validate(instance=valobj, schema=schema["schema-pycaosdb-ini"])
+    else:
+        warnings.warn("""
+                        Warning: The validation could not be performed because `jsonschema` is not installed.
+                    """)
 
 
 def _read_config_files():