diff --git a/synapse/handlers/auth.py b/synapse/handlers/auth.py
index 68d0d78fc..26c865e17 100644
--- a/synapse/handlers/auth.py
+++ b/synapse/handlers/auth.py
@@ -18,7 +18,7 @@ from twisted.internet import defer
 from ._base import BaseHandler
 from synapse.api.constants import LoginType
 from synapse.types import UserID
-from synapse.api.errors import AuthError, LoginError, Codes
+from synapse.api.errors import AuthError, LoginError, Codes, StoreError, SynapseError
 from synapse.util.async import run_on_reactor
 
 from twisted.web.client import PartialDownloadError
@@ -563,7 +563,12 @@ class AuthHandler(BaseHandler):
 
         except_access_token_ids = [requester.access_token_id] if requester else []
 
-        yield self.store.user_set_password_hash(user_id, password_hash)
+        try:
+            yield self.store.user_set_password_hash(user_id, password_hash)
+        except StoreError as e:
+            if e.code == 404:
+                raise SynapseError(404, "Unknown user", Codes.NOT_FOUND)
+            raise e
         yield self.store.user_delete_access_tokens(
             user_id, except_access_token_ids
         )