404 error app/api/user/route.ts with mongodb

I'm creating next.js project with mongodb. I completed to deploy to vercel. but i have a problem.

not working app/api/user/route.ts in deploy site. it is displayed 404 not found. but the data exist on mongodb and working on local. I don' know how to resolve it.

import { NextRequest, NextResponse } from "next/server";
import { connectDb } from "@/utils/database";
import { UserModel } from "@/models/userModel";

export const GET = async (request: NextRequest) => {
  try {
    await connectDb();

    // get name from query
    const { searchParams } = new URL(request.url);
    const name = searchParams.get("name");

    if (!name) {
      return NextResponse.json(
        { message: "message" },
        { status: 400 }
      );
    }

    const user = await UserModel.findOne({ name });

    if (user) {
      return NextResponse.json({
        message: "successful",
        user: user,
      });
    } else {
      return NextResponse.json(
        { message: "failed" },
        { status: 404 }
      );
    }
  } catch (error) {
    return NextResponse.json(
      { message: "failed" },
      { status: 500 }
    );
  }
};

↑this is my app/api/user/route.ts

import mongoose from "mongoose";

export const connectDb = async () => {
  try {
    await mongoose.connect(process.env.MONGODB_URI || "");
  } catch (error) {
    console.log("error");
    throw new Error();
  }
};

this is my utils/database.ts

 try {
      const response = await fetch(
        `${process.env.NEXT_PUBLIC_API_URL}/user?name=${encodeURIComponent(
          username
        )}`,
        {
          method: "GET",
        }
      );

      const data = await response.json();

      if (response.ok) {
        setUser(data.user);
      } else {
        setError(data.message);
      }
    } catch (error) {
      setError("failed");
    }

What is the problem.... (sorry.. I'm a beginner for English.)

import { NextRequest, NextResponse } from "next/server"; import { connectDb } from "@/utils/database"; import { UserModel } from "@/models/userModel"; export const GET = async (request: NextRequest) => { try { await connectDb(); // get name from query const { searchParams } = new URL(request.url); const name = searchParams.get("name"); if (!name) { return NextResponse.json( { message: "message" }, { status: 400 } ); } const user = await UserModel.findOne({ name }); if (user) { return NextResponse.json({ message: "successful", user: user, }); } else { return NextResponse.json( { message: "failed" }, { status: 404 } ); } } catch (error) { return NextResponse.json( { message: "failed" }, { status: 500 } ); } };

import mongoose from "mongoose"; export const connectDb = async () => { try { await mongoose.connect(process.env.MONGODB_URI || ""); } catch (error) { console.log("error"); throw new Error(); } };

try { const response = await fetch( `${process.env.NEXT_PUBLIC_API_URL}/user?name=${encodeURIComponent( username )}`, { method: "GET", } ); const data = await response.json(); if (response.ok) { setUser(data.user); } else { setError(data.message); } } catch (error) { setError("failed"); }