diff --git a/swh/objstorage/api/client.py b/swh/objstorage/api/client.py
--- a/swh/objstorage/api/client.py
+++ b/swh/objstorage/api/client.py
@@ -1,4 +1,4 @@
-# Copyright (C) 2015-2017  The Software Heritage developers
+# Copyright (C) 2015-2020  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
@@ -7,7 +7,7 @@
 from swh.model import hashutil
 
 from ..objstorage import DEFAULT_CHUNK_SIZE, DEFAULT_LIMIT
-from ..exc import ObjNotFoundError, ObjStorageAPIError
+from ..exc import Error, ObjNotFoundError, ObjStorageAPIError
 
 
 class RemoteObjStorage:
@@ -24,7 +24,10 @@
     """
 
     def __init__(self, **kwargs):
-        self._proxy = RPCClient(api_exception=ObjStorageAPIError, **kwargs)
+        self._proxy = RPCClient(
+            api_exception=ObjStorageAPIError,
+            reraise_exceptions=[ObjNotFoundError, Error],
+            **kwargs)
 
     def check_config(self, *, check_write):
         return self._proxy.post('check_config', {'check_write': check_write})
@@ -47,11 +50,7 @@
         return self.add(content, obj_id, check_presence=False)
 
     def get(self, obj_id):
-        ret = self._proxy.post('content/get', {'obj_id': obj_id})
-        if ret is None:
-            raise ObjNotFoundError(obj_id)
-        else:
-            return ret
+        return self._proxy.post('content/get', {'obj_id': obj_id})
 
     def get_batch(self, obj_ids):
         return self._proxy.post('content/get/batch', {'obj_ids': obj_ids})
diff --git a/swh/objstorage/api/server.py b/swh/objstorage/api/server.py
--- a/swh/objstorage/api/server.py
+++ b/swh/objstorage/api/server.py
@@ -1,4 +1,4 @@
-# Copyright (C) 2015-2019  The Software Heritage developers
+# Copyright (C) 2015-2020  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
@@ -18,7 +18,7 @@
 from swh.model import hashutil
 from swh.objstorage import get_objstorage
 from swh.objstorage.objstorage import DEFAULT_LIMIT
-from swh.objstorage.exc import ObjNotFoundError
+from swh.objstorage.exc import Error, ObjNotFoundError
 from swh.core.statsd import statsd
 
 
@@ -66,19 +66,13 @@
 @timed
 async def get_bytes(request):
     req = await decode_request(request)
-    try:
-        ret = request.app['objstorage'].get(**req)
-    except ObjNotFoundError:
-        ret = {
-            'error': 'object_not_found',
-            'request': req,
-        }
-        return encode_data(ret, status=404)
-    else:
-        statsd.increment('swh_objstorage_out_bytes_total',
-                         len(ret),
-                         tags={'endpoint': 'get_bytes'})
-        return encode_data(ret)
+
+    ret = request.app['objstorage'].get(**req)
+
+    statsd.increment('swh_objstorage_out_bytes_total',
+                     len(ret),
+                     tags={'endpoint': 'get_bytes'})
+    return encode_data(ret)
 
 
 @timed
@@ -177,6 +171,8 @@
     """
     client_max_size = config.get('client_max_size', 1024 * 1024 * 1024)
     app = RPCServerApp(client_max_size=client_max_size)
+    app.client_exception_classes = (ObjNotFoundError, Error)
+
     # retro compatibility configuration settings
     app['config'] = config
     _cfg = config['objstorage']