diff --git a/swh/web/ui/views/api.py b/swh/web/ui/views/api.py
--- a/swh/web/ui/views/api.py
+++ b/swh/web/ui/views/api.py
@@ -25,7 +25,7 @@
 
 @app.route('/api/1/search/', methods=['POST'])
 @app.route('/api/1/search/<string:q>/')
-def api_search(q):
+def api_search(q=None):
     """Search a content per hash.
 
     Args:
@@ -64,7 +64,7 @@
         # Remove potential inputs with no associated value
         for k, v in data.items():
             if v is not None:
-                if k == 'q':
+                if k == 'q' and len(v) > 0:
                     queries.append({'filename': None, 'sha1': v})
                 elif v != '':
                     queries.append({'filename': k, 'sha1': v})