diff --git a/apps/hub/app/(auth)/register/action.ts b/apps/hub/app/(auth)/register/action.ts
index 31c4fba8..a15bf2df 100644
--- a/apps/hub/app/(auth)/register/action.ts
+++ b/apps/hub/app/(auth)/register/action.ts
@@ -1,6 +1,8 @@
 "use server";
 import { prisma, Prisma } from "@repo/db";
 import bcrypt from "bcryptjs";
+import OLD_USER from "../../api/auth/[...nextauth]/var.User.json";
+import { OldUser } from "../../../types/oldUser";
 
 export const register = async ({ password, ...user }: Omit<Prisma.UserCreateInput, "publicId">) => {
 	const hashedPassword = await bcrypt.hash(password, 12);
@@ -26,12 +28,22 @@ export const register = async ({ password, ...user }: Omit<Prisma.UserCreateInpu
 			id: true,
 		},
 	});
+
+	const existingOldUser = (OLD_USER as OldUser[]).find((u) => u.email === user.email);
+
 	if (existingUser) {
 		return {
 			error: "Ein Nutzer mit dieser E-Mail-Adresse existiert bereits.",
 		};
 	}
 
+	if (existingOldUser) {
+		return {
+			error:
+				"Diese Email existriert bereits in der alten Version von VAR. Bitte melde dich an oder ändere dein Passwort.",
+		};
+	}
+
 	const newUser = prisma.user.create({
 		data: {
 			...user,