1 files changed, 1 insertions, 1 deletions
diff --git a/synapse/handlers/oidc_handler.py b/synapse/handlers/oidc_handler.py
index 55c4377890..c605f7082a 100644
--- a/synapse/handlers/oidc_handler.py
+++ b/synapse/handlers/oidc_handler.py
@@ -888,7 +888,7 @@ class OidcHandler(BaseHandler):
                 # continue to already be in use. Note that the error raised is
                 # arbitrary and will get turned into a MappingException.
                 if failures:
-                    raise RuntimeError(
+                    raise MappingException(
                         "Mapping provider does not support de-duplicating Matrix IDs"
                     )