diff --git a/changedetectionio/api/Import.py b/changedetectionio/api/Import.py
index 81b3d29b1..3f64739cd 100644
--- a/changedetectionio/api/Import.py
+++ b/changedetectionio/api/Import.py
@@ -9,6 +9,10 @@ import json
 # Number of URLs above which import switches to background processing
 IMPORT_SWITCH_TO_BACKGROUND_THRESHOLD = 20
 
+# Query params whose accepted values are wider than the `enum:` in the spec and are checked
+# separately further down (plugin processors aren't listed in the static spec enum).
+ENUM_VALIDATED_ELSEWHERE = {'processor'}
+
 
 def default_content_type(content_type='text/plain'):
     """Decorator to set a default Content-Type header if none is provided."""
@@ -143,10 +147,23 @@ class Import(Resource):
             # Convert to appropriate type based on schema
             try:
                 converted_value = convert_query_param_to_type(param_value, schema_properties[param_name])
-                extras[param_name] = converted_value
             except (ValueError, json.JSONDecodeError) as e:
                 return f"Invalid value for parameter '{param_name}': {str(e)}", 400
 
+            # Enforce any `enum:` declared in the OpenAPI spec (notification_format, method,
+            # conditions_match_logic ...). /api/v1/watch gets this for free because its JSON body is
+            # unmarshalled against the spec, but the import query params never were - so something
+            # like ?notification_format=Text used to be stored verbatim and then raise
+            # "Invalid notification format" at notification-send time, long after the import.
+            # `processor` is exempt: plugin processors are legal but aren't in the static spec enum,
+            # it has its own check against available_processors() below.
+            allowed_values = schema_properties[param_name].get('enum')
+            if allowed_values and param_name not in ENUM_VALIDATED_ELSEWHERE and converted_value not in allowed_values:
+                return (f"Invalid value for parameter '{param_name}': '{param_value}'. "
+                        f"Must be one of: {', '.join(str(v) for v in allowed_values)}"), 400
+
+            extras[param_name] = converted_value
+
         # Validate processor if provided
         if 'processor' in extras:
             from changedetectionio.processors import available_processors
diff --git a/changedetectionio/tests/test_api_openapi.py b/changedetectionio/tests/test_api_openapi.py
index 5628cc7f0..3c99c2c3d 100644
--- a/changedetectionio/tests/test_api_openapi.py
+++ b/changedetectionio/tests/test_api_openapi.py
@@ -56,6 +56,62 @@ def test_openapi_merged_spec_contains_restock_fields():
         f"WatchBase.processor_config_restock_diff should $ref the schema, got: {ref}"
 
 
+def test_openapi_notification_format_enum_matches_code():
+    """
+    Unit test: the notification_format enum in api-spec.yaml must stay in step with
+    valid_notification_formats, otherwise the API either rejects a format the UI offers or
+    accepts one that blows up when the notification object is built.
+    """
+    from changedetectionio.api import build_merged_spec_dict
+    from changedetectionio.notification import valid_notification_formats
+
+    spec = build_merged_spec_dict()
+    spec_enum = spec['components']['schemas']['WatchBase']['properties']['notification_format'].get('enum')
+
+    assert spec_enum is not None, "notification_format must declare an enum in api-spec.yaml"
+    assert set(spec_enum) == set(valid_notification_formats.keys()), \
+        (f"api-spec.yaml notification_format enum {spec_enum} does not match "
+         f"valid_notification_formats {list(valid_notification_formats.keys())}")
+
+
+def test_openapi_import_rejects_invalid_enum_query_param(client, live_server, measure_memory_usage, datastore_path):
+    """
+    /api/v1/import takes watch config as query params - those must honour the `enum:` in the spec.
+    'Text' is the classic one: it was the display name in an old release, so people still pass it,
+    and a stored 'Text' makes every notification for that watch raise ValueError at send time.
+    """
+    api_key = live_server.app.config['DATASTORE'].data['settings']['application'].get('api_access_token')
+
+    res = client.post(
+        url_for("import") + "?notification_format=Text",
+        data='https://website1.com',
+        headers={'x-api-key': api_key, 'content-type': 'text/plain'},
+    )
+    assert res.status_code == 400, f"Expected 400 but got {res.status_code}"
+    assert b'notification_format' in res.data
+    assert not live_server.app.config['DATASTORE'].data['watching'], "Nothing should have been imported"
+
+    # Another enum field on the same code path
+    res = client.post(
+        url_for("import") + "?method=FETCH",
+        data='https://website1.com',
+        headers={'x-api-key': api_key, 'content-type': 'text/plain'},
+    )
+    assert res.status_code == 400, f"Expected 400 but got {res.status_code}"
+
+    # ...and a valid value still imports and is stored
+    res = client.post(
+        url_for("import") + "?notification_format=htmlcolor",
+        data='https://website1.com',
+        headers={'x-api-key': api_key, 'content-type': 'text/plain'},
+    )
+    assert res.status_code == 200, f"Expected 200 but got {res.status_code}"
+    watch = live_server.app.config['DATASTORE'].data['watching'][res.json[0]]
+    assert watch.get('notification_format') == 'htmlcolor'
+
+    delete_all_watches(client)
+
+
 def test_openapi_validation_invalid_content_type_on_create_watch(client, live_server, measure_memory_usage, datastore_path):
     """Test that creating a watch with invalid content-type triggers OpenAPI validation error."""
     api_key = live_server.app.config['DATASTORE'].data['settings']['application'].get('api_access_token')