2 files changed, 9 insertions, 0 deletions
diff --git a/synapse/api/constants.py b/synapse/api/constants.py
index e0e24fddac..829061c870 100644
--- a/synapse/api/constants.py
+++ b/synapse/api/constants.py
@@ -79,6 +79,7 @@ class LoginType:
     TERMS = "m.login.terms"
     SSO = "m.login.sso"
     DUMMY = "m.login.dummy"
+    REGISTRATION_TOKEN = "org.matrix.msc3231.login.registration_token"
 
 
 # This is used in the `type` parameter for /register when called by
diff --git a/synapse/api/errors.py b/synapse/api/errors.py
index dc662bca83..9480f448d7 100644
--- a/synapse/api/errors.py
+++ b/synapse/api/errors.py
@@ -147,6 +147,14 @@ class SynapseError(CodeMessageException):
         return cs_error(self.msg, self.errcode)
 
 
+class InvalidAPICallError(SynapseError):
+    """You called an existing API endpoint, but fed that endpoint
+    invalid or incomplete data."""
+
+    def __init__(self, msg: str):
+        super().__init__(HTTPStatus.BAD_REQUEST, msg, Codes.BAD_JSON)
+
+
 class ProxiedRequestError(SynapseError):
     """An error from a general matrix endpoint, eg. from a proxied Matrix API call.