xcode 実機テストが真っ白になってしまう。（結果が表示されない）

前提・実現したいこと

昨日（8/29）までiPhoneやシュミレーターではちゃんと結果が出ました。
しかし、今日（2020/08/30）になって急に真っ白になってしまいました。
ドットインストールで、ブラウザーサイトを作っていました。
ViewController.swiftは赤いエラーは出ていませんでした。

発生している問題・エラーメッセージ

Thread 1: Exception: "[<mystopwatchapp.ViewController 0x7fb3cf408c90> setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key resetbutton2."

該当のソースコード

swiftです。
1//
2//  AppDelegate.swift
3//  mystopwatchapp
4//
5//  Created by user on 2020/08/22.
6//  Copyright © 2020 user. All rights reserved.
7//
8
9import UIKit
10
11@UIApplicationMain
12**class AppDelegate: UIResponder, UIApplicationDelegate **{
13
14
15
16    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
17        // Override point for customization after application launch.
18        return true
19    }
20
21    // MARK: UISceneSession Lifecycle
22
23    func application(_ application: UIApplication, configurationForConnecting connectingSceneSession: UISceneSession, options: UIScene.ConnectionOptions) -> UISceneConfiguration {
24        // Called when a new scene session is being created.
25        // Use this method to select a configuration to create the new scene with.
26        return UISceneConfiguration(name: "Default Configuration", sessionRole: connectingSceneSession.role)
27    }
28
29    func application(_ application: UIApplication, didDiscardSceneSessions sceneSessions: Set<UISceneSession>) {
30        // Called when the user discards a scene session.
31        // If any sessions were discarded while the application was not running, this will be called shortly after application:didFinishLaunchingWithOptions.
32        // Use this method to release any resources that were specific to the discarded scenes, as they will not return.
33    }
34
35
36}
37

試したこと

同じような質問がありましたが、うまくいきませんでした。

補足情報（FW/ツールのバージョンなど）

ViewControllerの中身です。

//
//  ViewController.swift
//  mystopwatchapp
//
//  Created by user on 2020/08/22.
//  Copyright © 2020 user. All rights reserved.
//

import UIKit

class ViewController: UIViewController {

    
    
    @IBOutlet weak var timerLavel: UILabel!
    @IBOutlet weak var startButton: UIButton!
    @IBOutlet weak var stopButton: UIButton!
    @IBOutlet weak var resetButton: UIButton!
    
    
    @IBOutlet weak var timerLavel2: UILabel!
    @IBOutlet weak var startButton2: UIButton!
    @IBOutlet weak var stopButton2: UIButton!
    @IBOutlet weak var resetButton2: UIButton!
    
    
    
    
    
    var startTime: TimeInterval? = nil
    var timer = Timer()
    var elapsedTime: Double = 0.0
    
    
    override func viewDidLoad() {
        super.viewDidLoad()
        // start: true, stop: false, reset: false
        setButtonEanble(start: true, stop: false, reset: false)
        // Do any additional setup after loading the view.
        
        //startButton.layer.borderWidth = 2
        //startButton.layer.borderColor = UIColor.orange.cgColor
        // myLabel.layer.borderWidth = 5
         //startButton.layer.cornerRadius = 50
        startButton.layer.masksToBounds = true
        startButton.layer.cornerRadius = startButton.bounds.width / 2
        stopButton.layer.masksToBounds = true
        stopButton.layer.cornerRadius = startButton.bounds.width / 2
        
        //resetButton.layer.masksToBounds = true
        //resetButton.layer.cornerRadius = startButton.bounds.width / 2
        
        
    }
    
    func setButtonEanble(start: Bool, stop: Bool, reset:Bool) {
        self.startButton.isEnabled = start
        self.stopButton.isEnabled = stop
        self.resetButton.isEnabled = reset
    }
    

    
    @objc func update() {
        // 2001/1/1 00:00:00:
    //  print(Date.timeIntervalSinceReferenceDate)
        if let startTime = self.startTime {
            let t: Double = Date.timeIntervalSinceReferenceDate - startTime + self.elapsedTime
            //print(t)
            let min = Int(t / 60)
            let sec = Int(t) % 60
            let msec = Int(t * 100) % 100
            let mmsec = Int(t * 100 * 100 ) % 100
            let mmmsec = Int(t * 100 * 100 * 100) % 100
            let mmmmsec = Int(t * 100 * 100 * 100 * 100) % 100
            let mmmmmsec = Int(t * 100 * 100 * 100 * 100 * 100) % 100
            self.timerLavel.text = String(format: "%02d:%02d:%02d:%02d:%02d:%02d:%02d", min, sec, msec, mmsec, mmmsec, mmmmsec, mmmmmsec)
        }
  }
    
    @IBAction func startTimer(_ sender: Any) {
        // start: true, stop: false, reset: false
        setButtonEanble(start: false, stop: true, reset: false)
        self.startTime = Date.timeIntervalSinceReferenceDate
        self.timer = Timer.scheduledTimer(
            timeInterval: 0.01,
            target: self,
            selector: #selector(self.update),
            userInfo: nil,
            repeats: true)
    }
    @IBAction func stopTimer(_ sender: Any) {
        // start: true, stop: false, reset: true
        setButtonEanble(start: true, stop: false, reset: true)
        if let startTime = self.startTime {
            self.elapsedTime += Date.timeIntervalSinceReferenceDate - startTime
        }
        self.timer.invalidate()
    }
    
    @IBAction func resetTimer(_ sender: Any) {
        // start: true, stop: false, reset: false
        setButtonEanble(start: true, stop: false, reset: false)
        self.startTime = nil
        self.timerLavel.text = "00:00:00:00:00:00:00"
        self.elapsedTime = 0.0
    }
}