.map is not a function in React Js [duplicate]

I create a page for display members of the sport club using MERN stack. I will mention below that code. In the browser, display the error as

members.map is not a function

I want to solve that error

import React, { useEffect, useState } from "react";
import Button from "react-bootstrap/Button";
import "bootstrap/dist/css/bootstrap.min.css";
import "../../css/Admin.css";
import AdminNavbar from "./AdminNavbar";
import axios from "axios";

function MemberDashboard() {
  const [members, setMembers] = useState([]);
  const [isLoading, setLoading] = useState(false);

  useEffect(() => {
    const fetchData = async () => {
      try {
        const response = await axios.get("http://localhost:8000/posts");
        setMembers(response.data);
      } catch (error) {
        console.error("Error fetching members:", error.message);
      }
    };

    fetchData();
    function simulateNetworkRequest() {
      return new Promise((resolve) => setTimeout(resolve, 2000));
    }

    if (isLoading) {
      simulateNetworkRequest().then(() => {
        setLoading(false);
      });
    }
  }, [isLoading]);

  const handleActionClick = () => setLoading(true);

  return (
    <div>
      <div className="navshadow">
        <AdminNavbar />
      </div>
      <h1>Members of Sports Club</h1>
      <br />
      <table className="members">
        <thead>
          <tr>
            <th>No.</th>
            <th>Name</th>
            <th>Email</th>
            <th>Phone</th>
            <th>Action</th>
          </tr>
        </thead>
        <tbody>
          {members ? (
            members.map((member, index) => (
              <tr key={index}>
                <td>{index + 1}</td>
                <td>{`${member.fname} ${member.lname}`}</td>
                <td>{member.email || "-"}</td>
                <td>{member.phone || "-"}</td>
                <td>
                  <Button
                    variant="primary"
                    size="sm"
                    className="me-4"
                    disabled={isLoading}
                    onClick={!isLoading ? handleActionClick : null}
                  >
                    {isLoading ? "Loading…" : "Edit"}
                  </Button>

                  <Button
                    variant="danger"
                    size="sm"
                    disabled={isLoading}
                    onClick={!isLoading ? handleActionClick : null}
                  >
                    {isLoading ? "Loading…" : "DELETE"}
                  </Button>
                </td>
              </tr>
            ))
          ) : (
            <tr>
              <td colSpan="5">No members found</td>
            </tr>
          )}
        </tbody>
      </table>
    </div>
  );
}

export default MemberDashboard;

I want to solve above error and I want to know reason for that.