Full Script

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Networking;
using TMPro;
 
public class PasswordChange : MonoBehaviour
{
    public TMP_InputField current_password;
    public TMP_InputField new_password;
    public TMP_InputField new_password_confirm;
    public TextMeshProUGUI username;
 
    public PopUpSystem popUp;
 
    public void ButtonChangePassword()
    {
        if (new_password.text != new_password_confirm.text)
        {
            popUp.OpenPopUp("ERROR!", "new password didn't match");
            return;
        }
 
        if (new_password.text.Length <= 6)
        {
            popUp.OpenPopUp("ERROR!", "Field cannot be empty");
        }
 
        if (current_password.text == "" || new_password.text == "" || new_password_confirm.text == "")
        {
            popUp.OpenPopUp("ERROR!", "Field cannot be empty");
            return;
        }
 
        StartCoroutine(Upload());
    }
 
    IEnumerator Upload()
    {
        WWWForm form = new WWWForm();
        form.AddField("playerUsername", username.text);
        form.AddField("currentPassword", current_password.text);
        form.AddField("newPassword", new_password.text);
 
        using (UnityWebRequest www = UnityWebRequest.Post("hidden", form))
        {
            yield return www.SendWebRequest();
 
            if (www.result != UnityWebRequest.Result.Success)
            {
                Debug.Log(www.error);
            }
            else
            {
                if(www.downloadHandler.text.Equals("Password Changed."))
                {
                    popUp.OpenPopUp("ERROR!", "Password Changed.");
                }
 
                if (www.downloadHandler.text.Equals("Wrong Current Password Entered."))
                {
                    popUp.OpenPopUp("ERROR!", "Wrong Current Password Entered.");
 
                }
 
                if (www.downloadHandler.text.Equals("Error! Please if you find the message contact us at admin@gementar.com"))
                {
                    popUp.OpenPopUp("ERROR!", "Error! Please if you find the message contact us at admin@gementar.com");
                }
 
                Debug.Log(www.downloadHandler.text);
 
            }
        }
    }
}