diff --git a/src/server/api/private/signup.ts b/src/server/api/private/signup.ts
index b8793582f..d535d4983 100644
--- a/src/server/api/private/signup.ts
+++ b/src/server/api/private/signup.ts
@@ -117,7 +117,7 @@ export default async (ctx: Koa.BaseContext) => {
 			host: null
 		});
 
-		if (exist) throw 'already registered';
+		if (exist) throw new Error(' the username is already used');
 
 		account = await transactionalEntityManager.save(new User({
 			id: genId(),