diff --git a/swh/graphql/resolvers/scalars.py b/swh/graphql/resolvers/scalars.py
--- a/swh/graphql/resolvers/scalars.py
+++ b/swh/graphql/resolvers/scalars.py
@@ -10,6 +10,7 @@
 from swh.graphql.errors import InvalidInputError
 from swh.graphql.utils import utils
 from swh.model import hashutil
+from swh.model.exceptions import ValidationError
 from swh.model.model import TimestampWithTimezone
 from swh.model.swhids import CoreSWHID
 
@@ -38,7 +39,11 @@
 
 @swhid_scalar.value_parser
 def validate_swhid(value):
-    return CoreSWHID.from_string(value)
+    try:
+        swhid = CoreSWHID.from_string(value)
+    except ValidationError as e:
+        raise InvalidInputError("Invalid SWHID", e)
+    return swhid
 
 
 @swhid_scalar.serializer
diff --git a/swh/graphql/server.py b/swh/graphql/server.py
--- a/swh/graphql/server.py
+++ b/swh/graphql/server.py
@@ -65,7 +65,7 @@
     from starlette.middleware.cors import CORSMiddleware
 
     from .app import schema
-    from .errors.handlers import format_error
+    from .errors import format_error
 
     global graphql_cfg
 
diff --git a/swh/graphql/tests/conftest.py b/swh/graphql/tests/conftest.py
--- a/swh/graphql/tests/conftest.py
+++ b/swh/graphql/tests/conftest.py
@@ -10,6 +10,7 @@
 
 from swh.graphql import server as app_server
 from swh.graphql.app import schema
+from swh.graphql.errors import format_error
 from swh.search import get_search as get_swh_search
 from swh.storage import get_storage as get_swh_storage
 
@@ -46,7 +47,11 @@
         # GraphQL queries are always sent as POST
         data = request.get_json()
         success, result = graphql_sync(
-            schema, data, context_value=request, debug=app.debug
+            schema,
+            data,
+            context_value=request,
+            debug=app.debug,
+            error_formatter=format_error,
         )
         status_code = 200 if success else 400
         return jsonify(result), status_code
diff --git a/swh/graphql/tests/functional/test_content.py b/swh/graphql/tests/functional/test_content.py
--- a/swh/graphql/tests/functional/test_content.py
+++ b/swh/graphql/tests/functional/test_content.py
@@ -93,7 +93,7 @@
     errors = utils.get_error_response(client, query_str)
     # API will throw an error in case of an invalid SWHID
     assert len(errors) == 1
-    assert "Invalid SWHID: invalid syntax" in errors[0]["message"]
+    assert "Input error: Invalid SWHID" in errors[0]["message"]
 
 
 def test_get_content_with_invalid_hashes(client):
diff --git a/swh/graphql/tests/functional/test_directory.py b/swh/graphql/tests/functional/test_directory.py
--- a/swh/graphql/tests/functional/test_directory.py
+++ b/swh/graphql/tests/functional/test_directory.py
@@ -33,7 +33,7 @@
     errors = utils.get_error_response(client, query_str)
     # API will throw an error in case of an invalid SWHID
     assert len(errors) == 1
-    assert "Invalid SWHID: invalid syntax" in errors[0]["message"]
+    assert "Input error: Invalid SWHID" in errors[0]["message"]
 
 
 def test_get_revision_directory(client):
diff --git a/swh/graphql/tests/functional/test_revision.py b/swh/graphql/tests/functional/test_revision.py
--- a/swh/graphql/tests/functional/test_revision.py
+++ b/swh/graphql/tests/functional/test_revision.py
@@ -83,7 +83,7 @@
     errors = utils.get_error_response(client, query_str)
     # API will throw an error in case of an invalid SWHID
     assert len(errors) == 1
-    assert "Invalid SWHID: invalid syntax" in errors[0]["message"]
+    assert "Input error: Invalid SWHID" in errors[0]["message"]
 
 
 def test_get_revision_as_target(client):
diff --git a/swh/graphql/tests/functional/test_snapshot_node.py b/swh/graphql/tests/functional/test_snapshot_node.py
--- a/swh/graphql/tests/functional/test_snapshot_node.py
+++ b/swh/graphql/tests/functional/test_snapshot_node.py
@@ -54,4 +54,4 @@
     """
     errors = get_error_response(client, query_str)
     assert len(errors) == 1
-    assert "Invalid SWHID: invalid syntax" in errors[0]["message"]
+    assert "Input error: Invalid SWHID" in errors[0]["message"]
diff --git a/swh/graphql/tests/functional/test_swhid_resolve.py b/swh/graphql/tests/functional/test_swhid_resolve.py
--- a/swh/graphql/tests/functional/test_swhid_resolve.py
+++ b/swh/graphql/tests/functional/test_swhid_resolve.py
@@ -28,7 +28,7 @@
     errors = utils.get_error_response(client, query_str)
     # API will throw an error in case of an invalid SWHID
     assert len(errors) == 1
-    assert "Invalid SWHID: invalid syntax" in errors[0]["message"]
+    assert "Input error: Invalid SWHID" in errors[0]["message"]
 
 
 @pytest.mark.parametrize(