diff --git a/src/github.com/matrix-org/dendrite/clientapi/routing/register.go b/src/github.com/matrix-org/dendrite/clientapi/routing/register.go
index 4f267532d..cb427b710 100644
--- a/src/github.com/matrix-org/dendrite/clientapi/routing/register.go
+++ b/src/github.com/matrix-org/dendrite/clientapi/routing/register.go
@@ -415,7 +415,7 @@ func Register(
 	if r.Username == "" {
 		id, err := accountDB.GetNewNumericLocalpart(req.Context())
 		if err != nil {
-			return jsonerror.InternalServerError()
+			return httputil.LogThenError(req, err)
 		}
 
 		r.Username = strconv.FormatInt(id, 10)