diff --git a/swh/web/common/identifiers.py b/swh/web/common/identifiers.py
--- a/swh/web/common/identifiers.py
+++ b/swh/web/common/identifiers.py
@@ -115,7 +115,7 @@
 
     if query_params and len(query_params) > 0:
         for k in sorted(query_params.keys()):
-            query_dict[k] = query_params[k]
+            query_dict[k] = str(query_params[k])
 
     if swhid_parsed.origin:
         origin_url = unquote(swhid_parsed.origin)
@@ -150,14 +150,11 @@
                     query_dict["path"] = hash_to_hex(directory) + query_dict["path"]
                 else:
                     # remove leading slash from SWHID content path
-                    query_dict["path"] = query_dict["path"][1:]
+                    query_dict["path"] = str(query_dict["path"]).lstrip("/")
             elif object_type == ObjectType.DIRECTORY:
                 object_id = directory
                 # remove leading and trailing slashes from SWHID directory path
-                if query_dict["path"].endswith("/"):
-                    query_dict["path"] = query_dict["path"][1:-1]
-                else:
-                    query_dict["path"] = query_dict["path"][1:]
+                query_dict["path"] = str(query_dict["path"]).strip("/")
 
     # snapshot context
     if swhid_parsed.visit:
diff --git a/swh/web/common/utils.py b/swh/web/common/utils.py
--- a/swh/web/common/utils.py
+++ b/swh/web/common/utils.py
@@ -101,7 +101,7 @@
     if query_params and len(query_params) > 0:
         query_dict = QueryDict("", mutable=True)
         for k in sorted(query_params.keys()):
-            query_dict[k] = query_params[k]
+            query_dict[k] = str(query_params[k])
         url += "?" + query_dict.urlencode(safe="/;:")
 
     if request is not None:
diff --git a/swh/web/tests/conftest.py b/swh/web/tests/conftest.py
--- a/swh/web/tests/conftest.py
+++ b/swh/web/tests/conftest.py
@@ -21,7 +21,7 @@
 
 from django.contrib.auth.models import User
 from django.core.cache import cache
-from django.test.utils import setup_databases  # type: ignore
+from django.test.utils import setup_databases
 from rest_framework.test import APIClient, APIRequestFactory
 
 from swh.model.hashutil import (
diff --git a/swh/web/tests/utils.py b/swh/web/tests/utils.py
--- a/swh/web/tests/utils.py
+++ b/swh/web/tests/utils.py
@@ -7,7 +7,7 @@
 
 from django.contrib.auth.models import Permission
 from django.contrib.contenttypes.models import ContentType
-from django.http import HttpResponse, StreamingHttpResponse
+from django.http.response import HttpResponse, HttpResponseBase, StreamingHttpResponse
 from django.test.client import Client
 from rest_framework.response import Response
 from rest_framework.test import APIClient
@@ -16,8 +16,8 @@
 
 
 def _assert_http_response(
-    response: HttpResponse, status_code: int, content_type: str
-) -> HttpResponse:
+    response: HttpResponseBase, status_code: int, content_type: str
+) -> HttpResponseBase:
 
     if isinstance(response, Response):
         drf_response = cast(Response, response)
@@ -28,7 +28,7 @@
         )
     elif isinstance(response, StreamingHttpResponse):
         error_context = getattr(response, "traceback", response.streaming_content)
-    else:
+    elif isinstance(response, HttpResponse):
         error_context = getattr(response, "traceback", response.content)
 
     assert response.status_code == status_code, error_context
@@ -44,7 +44,7 @@
     content_type: str = "*/*",
     http_origin: Optional[str] = None,
     server_name: Optional[str] = None,
-) -> HttpResponse:
+) -> HttpResponseBase:
     """Helper function to check HTTP response for a GET request.
 
     Args:
@@ -77,7 +77,7 @@
     request_content_type="application/json",
     data: Optional[Dict[str, Any]] = None,
     http_origin: Optional[str] = None,
-) -> HttpResponse:
+) -> HttpResponseBase:
     """Helper function to check HTTP response for a POST request.
 
     Args:
@@ -140,7 +140,7 @@
     status_code: int,
     content_type: str = "*/*",
     data: Optional[Dict[str, Any]] = None,
-) -> HttpResponse:
+) -> HttpResponseBase:
     """Helper function to check Web API response for a POST request
     for all accepted content types.
 
@@ -201,7 +201,7 @@
     template_used: Optional[str] = None,
     http_origin: Optional[str] = None,
     server_name: Optional[str] = None,
-) -> HttpResponse:
+) -> HttpResponseBase:
     """Helper function to check HTML responses for a GET request.
 
     Args: