1 files changed, 2 insertions, 7 deletions
diff --git a/synapse/handlers/register.py b/synapse/handlers/register.py
index a2d3f03061..3a55056df5 100644
--- a/synapse/handlers/register.py
+++ b/synapse/handlers/register.py
@@ -143,15 +143,10 @@ class RegistrationHandler:
         assigned_user_id: Optional[str] = None,
         inhibit_user_in_use_error: bool = False,
     ) -> None:
-        if types.contains_invalid_mxid_characters(
-            localpart, self.hs.config.experimental.msc4009_e164_mxids
-        ):
-            extra_chars = (
-                "=_-./+" if self.hs.config.experimental.msc4009_e164_mxids else "=_-./"
-            )
+        if types.contains_invalid_mxid_characters(localpart):
             raise SynapseError(
                 400,
-                f"User ID can only contain characters a-z, 0-9, or '{extra_chars}'",
+                "User ID can only contain characters a-z, 0-9, or '=_-./+'",
                 Codes.INVALID_USERNAME,
             )