diff --git a/swh/vault/tests/test_server.py b/swh/vault/tests/test_server.py
index bd96ef4..6072e54 100644
--- a/swh/vault/tests/test_server.py
+++ b/swh/vault/tests/test_server.py
@@ -1,157 +1,157 @@
 # Copyright (C) 2020  The Software Heritage developers
 # See the AUTHORS file at the top-level directory of this distribution
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
 import copy
 import os
 from typing import Any, Dict
 
 import pytest
 import yaml
 
 from swh.core.api.serializers import json_dumps, msgpack_dumps, msgpack_loads
 from swh.vault.api.server import (
     VaultServerApp,
     check_config,
     make_app,
     make_app_from_configfile,
 )
 from swh.vault.tests.test_backend import TEST_HEX_ID
 
 
 def test_make_app_from_file_missing():
     with pytest.raises(ValueError, match="Missing configuration path."):
         make_app_from_configfile()
 
 
 def test_make_app_from_file_does_not_exist(tmp_path):
     conf_path = os.path.join(str(tmp_path), "vault-server.yml")
     assert os.path.exists(conf_path) is False
 
     with pytest.raises(
         ValueError, match=f"Configuration path {conf_path} should exist."
     ):
         make_app_from_configfile(conf_path)
 
 
 def test_make_app_from_env_variable(swh_vault_config_file):
     """Server initialization happens through env variable when no path is provided
 
     """
     app = make_app_from_configfile()
     assert app is not None
 
 
 def test_make_app_from_file(swh_local_vault_config, tmp_path):
     """Server initialization happens trough path if provided
 
     """
     conf_path = os.path.join(str(tmp_path), "vault-server.yml")
     with open(conf_path, "w") as f:
         f.write(yaml.dump(swh_local_vault_config))
 
     app = make_app_from_configfile(conf_path)
     assert app is not None
 
 
 @pytest.fixture
 def async_app(swh_local_vault_config: Dict[str, Any],) -> VaultServerApp:
     """Instantiate the vault server application.
 
     Note: This requires the db setup to run (fixture swh_vault in charge of this)
 
     """
     return make_app(swh_local_vault_config)
 
 
 @pytest.fixture
 def cli(async_app, aiohttp_client, loop):
     return loop.run_until_complete(aiohttp_client(async_app))
 
 
 async def test_client_index(cli):
     resp = await cli.get("/")
     assert resp.status == 200
 
 
 async def test_client_cook_notfound(cli):
     resp = await cli.post(
         "/cook",
         data=json_dumps({"obj_type": "directory", "obj_id": TEST_HEX_ID}),
         headers=[("Content-Type", "application/json")],
     )
     assert resp.status == 400
     content = msgpack_loads(await resp.content.read())
-    assert content["exception"]["type"] == "NotFoundExc"
-    assert content["exception"]["args"] == [f"directory {TEST_HEX_ID} was not found."]
+    assert content["type"] == "NotFoundExc"
+    assert content["args"] == [f"directory {TEST_HEX_ID} was not found."]
 
 
 async def test_client_progress_notfound(cli):
     resp = await cli.post(
         "/progress",
         data=json_dumps({"obj_type": "directory", "obj_id": TEST_HEX_ID}),
         headers=[("Content-Type", "application/json")],
     )
     assert resp.status == 400
     content = msgpack_loads(await resp.content.read())
-    assert content["exception"]["type"] == "NotFoundExc"
-    assert content["exception"]["args"] == [f"directory {TEST_HEX_ID} was not found."]
+    assert content["type"] == "NotFoundExc"
+    assert content["args"] == [f"directory {TEST_HEX_ID} was not found."]
 
 
 async def test_client_batch_cook_invalid_type(cli):
     resp = await cli.post(
         "/batch_cook",
         data=msgpack_dumps({"batch": [("foobar", [])]}),
         headers={"Content-Type": "application/x-msgpack"},
     )
     assert resp.status == 400
     content = msgpack_loads(await resp.content.read())
-    assert content["exception"]["type"] == "NotFoundExc"
-    assert content["exception"]["args"] == ["foobar is an unknown type."]
+    assert content["type"] == "NotFoundExc"
+    assert content["args"] == ["foobar is an unknown type."]
 
 
 async def test_client_batch_progress_notfound(cli):
     resp = await cli.post(
         "/batch_progress",
         data=msgpack_dumps({"batch_id": 1}),
         headers={"Content-Type": "application/x-msgpack"},
     )
     assert resp.status == 400
     content = msgpack_loads(await resp.content.read())
-    assert content["exception"]["type"] == "NotFoundExc"
-    assert content["exception"]["args"] == ["Batch 1 does not exist."]
+    assert content["type"] == "NotFoundExc"
+    assert content["args"] == ["Batch 1 does not exist."]
 
 
 def test_check_config_missing_vault_configuration() -> None:
     """Irrelevant configuration file path raises"""
     with pytest.raises(ValueError, match="missing 'vault' configuration"):
         check_config({})
 
 
 def test_check_config_not_local() -> None:
     """Wrong configuration raises"""
     expected_error = (
         "The vault backend can only be started with a 'local' configuration"
     )
     with pytest.raises(EnvironmentError, match=expected_error):
         check_config({"vault": {"cls": "remote"}})
 
 
 @pytest.mark.parametrize("missing_key", ["storage", "cache", "scheduler"])
 def test_check_config_missing_key(missing_key, swh_vault_config) -> None:
     """Any other configuration than 'local' (the default) is rejected"""
     config_ok = {"vault": {"cls": "local", **swh_vault_config}}
     config_ko = copy.deepcopy(config_ok)
     config_ko["vault"].pop(missing_key, None)
 
     expected_error = f"invalid configuration: missing {missing_key} config entry"
     with pytest.raises(ValueError, match=expected_error):
         check_config(config_ko)
 
 
 @pytest.mark.parametrize("missing_key", ["storage", "cache", "scheduler"])
 def test_check_config_ok(missing_key, swh_vault_config) -> None:
     """Any other configuration than 'local' (the default) is rejected"""
     config_ok = {"vault": {"cls": "local", **swh_vault_config}}
     assert check_config(config_ok) is not None