Recently, I have been getting this request where people are asking me questions on how to solve the prohibitory sign at the end of a MacBook booting up procedure.

If you are using a MacBook for a long period of time, there is a chance that you will encounter this problem at some corner of your life. It is a common problem that follows after an infinite boot-up loop.

This problem usually happens when your system tries to start up but doesn’t get a hold of the start-up volume to connect the link between your device and the operating system. The problem is easy to identify as it comes with a grey screen and a Mac prohibitory symbol in the centre of the screen.

How to Fix the Prohibitory Sign Problem?

Before starting with the solutions, let’s first understand the reasons behind this issue. To make it clear, when you boot up your Mac but only to see a circle with a line through, it means your hardware does detect an operating system but the macOS does not work with your current device. Therefore, the most straightforward way to troubleshoot Mac prohibitory sign is to reinstall a new compatible macOS, or downgrade your operating system to make it work with the Mac module you are using. 

Unfortunately, reinstalling macOS will first wipe out all your previous data in the start-up drive. For most users, the start-up drive contains lots of important files within and to save your precious data, you are highly recommended to use professional data recovery software like iBoysoft Data Recovery. This powerful data recovery tool can take very good care of the data you want to recover. After that, you can move on to reinstalling macOS. 

Steps to reinstall macOS

Step 1: Boot into Recovery mode

First, you have to boot your Mac into recovery mode from either local recovery system or internet recovery system. Both recovery systems can work. Below are the steps to boot into standard recovery mode.

• Shut down your MacBook by force by holding the power button or the Touch ID.
• Restart the device and immediately hold Command + R key combinations. 
• Let go of the buttons if any logo or sign show up. A macOS Utilities window should pop up if you are in the Recovery mode. 

Step 2: Run Disk Utility in recovery mode

All the macOS come with a Disk Utility menu to handle situations like this. It allows the user to check the drive and repair it, but frankly speaking, this tool offers limited function.

Just click on the start-up drive, select First Aid on the top of the menu, and the system will detect errors and tries to fix them. If luckily, First Aid succeeds in fixing the corrupted system drive, users can quit Disk Utility and reboot the computer.

However, chances are the prohibitory sign still appears when you reboot the device. At this time, you can only move to the reinstalling process.

Step 3: Reinstall macOS (back up first!)

As what’s mentioned above, reinstalling macOS will erase all previous data. Therefore, you should either recover data first or have a backup plan. After that, click Reinstall macOS and then select Continue. You’ll have to select a folder to store the new operating system. Generally, it’s the Macintosh HD one. The rest for you to do is to follow onscreen steps. Now with everything freshly prepared, try reboot your computer, is it normal now?

Run Apple Hardware Test

If nothing is working in your favour, you can take help from the Apple hardware test.

• Disconnect everything from the system. Keep only the ethernet, mouse, keyboards, and display screen.
• Now shut down your system.
• Turn ON your system and when the screen shows signs of life, immediately Press D.
• Maintain the hold on D until the apple diagnostic test sign appears on the screen.
• Select the language before starting.
• Press T to start with the test.
• When the test is finished, the result will appear on the screen.
• Restart the system.

Was That Helpful?

With that being said, here is my list of solutions that might hold answers to solve your prohibitory sign problem. Every method mentioned in this article aims to solve the problem. Which method is going to work depends on the situation your computer is in.

Once you have solved your problem, do let us know which solution was helpful for you and leave a comment below!