Prohibitory Symbol Appears
Your Mac showing you a cross-out circle or Mac prohibitory symbol on your screen when you are booting up does not necessarily spell doom. Although it is a clear indication that there are some errors somewhere on your Mac, it already streamlines where you should concentrate your troubleshooting efforts.

One of the top benefits you enjoy from using a MacBook is the fact that its error indicators help you know what might be wrong when there is an error with your MacBook. This case, however, indicates that the data on your Mac might be in danger.

Cause of the Prohibitory Symbol on Mac Screen While Starting up

The prohibitory symbol on your Mac screen means that the operating system on the startup disk on your Mac is not compatible with your Mac model. It could also mean that the Mac is not detecting an operating system in your startup disk or the operating system on the startup disk does not contain the required files.

Another instance that can cause this error is that users have multiple operating systems on their MacBook. The conflicting files on the startup disk could also cause the prohibitory symbol feedback you are getting when you are starting up your Mac.

How to Fix the Error of a Prohibitory Symbol on Mac?

If you are looking for help to get past the crossed-out line or prohibitory symbol on your Mac, here are some applicable steps that can help you solve this error.

1. Repair your startup disk with the Disk Utility option

This method of solving the issue requires you to boot your Mac into macOS recovery mode. This is to access the macOS utility option on your Mac. Disk Utility is an option in the macOS utilities menu. Take the step-by-step procedure below as a reference to fix your startup disk.
  • Click and hold down the power button on your Mac for up to 10 seconds to force your Mac to switch off.
  • After 30 seconds, press the power button to switch it back on. Immediately click and hold the ‘Command’ and ‘R’ key combination for about five seconds or a little longer to start up your Mac in macOS recovery mode.
  • The macOS utilities function provides options for carrying out different operations. Select ‘Disk Utility’ to carry out the startup disk repair.
  • The left side of the Disk Utility menu displays all available disks on your Mac. The first disk option is the startup disk. For the startup disk, start your fix by selecting the last option in the disk menu. This is typically the volume of the disk. Click on the ‘First Aid’ button to commence repair. Do the same for the container and finally the disk itself.

2. Reinstall a new macOS

In a scenario where the ‘First Aid’ program does not pull through with the fix for your startup disk, this can only mean that the operating system on your device is incompatible with the model. Often time, this is a result of an upgrade to your current macOS. It could also be because the current macOS version on your Mac is faulty. Either way, reinstalling a macOS that works with your MacBook is the only way for you to fix the error you are currently facing.

The instalment of a new macOS version results in a data wipe from your Mac. Before the installation, recover your data using iBoysoft Data Recovery for Mac that is a great option to recover your data from an unbootable Mac in macOS recovery mode first, and then back up all the recovered data.

After you have backed all the important data up, it’s time to proceed with the macOS reinstallation.

Step 1 Boot your Mac into macOS recovery mode and then select the Reinstall macOS option listed on the macOS Utilities menu.

Step 2 Click on the Continue button and do as the onscreen instructions tell you to do to complete the macOS reinstallation.