How to Merge Hard Disk Partitions on Mac?

Apple provides a handy tool, Boot Camp Assitant, which helps users to install Windows on their Mac systems. The tool basically partitions your startup disk to add all the macOS files on one partition and installs Windows firmware on the other partition. Although it is a relatively safe process, many Mac users are facing a “disk could not be restored to a single partition” error on the Boot Camp Assitant. It is particularly happening when they are trying to remove Windows and restore the partition.

If you are also facing a “disk could not be restored to a single partition” error on your Boot Camp Assistant and do not know how to merge hard disk partitions. Therefore, in this article, we have included the best methods to fix the issue and help restore to single partition on your Mac. We have also provided detailed explanations and reasons for the error message, along with easy tips to prevent partition errors in the future.

Part 1: What Does "Disk Could Not Be Restored to A Single Partition" Error Mean

The “Disk could not be restored to a single partition” often occurs during the removal of Windows from your Mac. If you have encountered this issue, it often means that the Boot Camp Assitant is having difficulties removing Windows and restoring the boot disk to a single partition.

Boot Camp Assistant is a built-in macOS program that helps you create or delete a partition on your boot drive to install Windows or restore your Mac and remove Windows. The program is available for macOS that run on Intel-based Macs for all macOS versions. However, Mac computers with Apple silicon chips do not support Boot Camp. The boot camp error on the disk partition can occur for many reasons.

Here are some of the main reasons that can lead to the “restore to single partition” error:

• Sometimes, the issue can be caused by disk-related errors and faults.
• The error might happen due to a lack of free space on the startup disk.
• If you create two or more partitions on the startup disk, it might also create conflicts.

Part 2: How to Fix Restore to Single Partition Error on Mac

Now that you understand the reasons and the exact meaning of the “disk could not be restored to a single partition” error message. Let us move on to the part of the solutions about how to resolve the issue and how to merge hard disk partitions on Mac.

Method 1: Create Space on the Startup Disk

If you are wondering how to merge hard disk partitions in Mac? Especially after removing Windows from your system. You can use Disk Utility to achieve it. But what to do if you encounter a “disk could not be restored to a single partition” error message while trying to merge? As stated earlier, one of the most common reasons for the error message could be due to not enough space in the startup disk. Therefore, you can resolve the issue by creating space on the startup disk to allocate enough storage options for Boot Camp Assitant to work.

Here are the following steps you should follow to create space on the startup disk to fix and restore to single partition:

Step 1: First, click on the “Apple Menu” and select the “About This Mac” option.

Step 2: Next, select the “Storage” tab at the top and click on the “Manage” button.

Step 3: On the next window, click on the “Optimize” button next to the “Optimize Storage” section.

Step 4: Select all the unwanted files you want to remove from the list to free up disk space on the Mac.

Step 5: Furthermore, consider clearing the trash bin on your Mac. Click on the “Trash” icon on the “Dock” and select the “Empty Trash” option.

Step 6: Next, delete junk files by going to “Go to Folder” and entering “/var/log”. Select all the log files and click on the “Delete” option.

Step 7: Also, delete temporary files on your Mac to create more space, open the “Go to Finder” and enter “~/Library/Caches/”. Select all the temporary files and click on the “Delete” option.

Step 8: Furthermore, delete your browser cache, downloads, duplicates, and temporary files to make more space on the startup disk.

Method 2: Update Mac OS

Another straightforward solution to fix your disk could not be restored to a single partition error is to update macOS. If you are running an older version of macOS on your Mac, Boot Camp Assitant might face compatibility issues and show errors. Therefore, consider updating your Mac system if the latest version of the macOS is available.

Here are the following steps to update your Mac system to fix the restore to single partition issue:

Step 1: First, click on the “Apple Menu” at the top and select the “About this Mac” option from the drop-down.

Step 2: On the new window, click on the “Software update” option.

Step 3: Next, click on the “Update Now” if any latest update is available. Or, click on the “Restart Now” option if it has already been updated.

Method 3: Repair Boot Disk Using Disk Utility

If you are wondering, how do I make my Mac hard drive back to one partition after getting the disk could not be restored to a single partition error. You can fix it using the First Aid tool in Disk Utility on your Mac. It will scan for any errors in the partitions of the disk and repair it to fix any issues.

Here are the following steps to fix "restore to single partition" problem using Disk Utility:

Step 1: Launch “Finder” and go to “Applications”. Click on the “Utilities” option and select “Disk Utility” from the list.

Step 2: Next, on the Disk Utility window, select your boot disk on the left side panel, which is usually the one at the top of the list.

Step 3: Click on the “First Aid” option at the top to fix the startup disk.

Step 4: Lastly, click on the “Run” button on the pop-up window to confirm to start the repair process.

Step 5: Wait for the Disk Utility to scan the startup disk and try to repair it. After the process is completed, you can review the repair information to analyze.

Method 4: Check Unallocated Disk Space

Finally, you can also resolve your disk could not be restored to a single partition issue by adding more space to the startup disk. Often, your Mac hard drive contains unallocated disk space, which can be used for anything to store. However, you can use the unallocated disk space to expand your storage capacity and fix the issue.

Here are the following steps to fix your disk could not be restored to a single partition with unallocated free space:

Step 1: Launch “Finder” and go to “Applications”. Click on the “Utilities” option and select “Disk Utility” from the list.

Step 2: Select your boot disk from the left side panel, which is usually named Macintosh HD.

Step 3: Next, click on the “Partition” option at the top of the toolbar.

Step 4: When prompted on the pop-up window, click on the “Partition” option to confirm you want to partition.

Step 5: If you see any “Free Space” section on the pie chart, select it. Then, click on the “-” option at the bottom of the chart to remove the unallocated storage space and make it available.

Step 6: Ensure to click on the “Apply” button to save the changes. Restart your Mac to apply the storage changes, and then try running Boot Camp Assistant.

Part 3: How to Recover Lost Data on Mac

Often, when users face the “disk could not be restored to a single partition” error, they straight away move toward the solutions part. However, during restore to single partition process of your Mac might result in data loss. Unless you have already created a backup of the data, it is better to recover data before proceeding with solutions.

To achieve this, we highly recommend using the Recoverit Data Recovery tool, one of the reliable data recovery tools for Mac, which can easily recover all your data from any hard drive. Recoverit will recover any type of data you have lost, regardless of the reason for it. These covers retrieving data from a formatted hard drive, corrupted storage, trash deletion, inadvertent deletion, and so on.

Following are the steps to recover lost data on your Mac using Recoverit:

Step 1: First, download and install the Recoverit Data Recovery program on your Mac from its official website. However, make sure to install the application in a different drive from where you want to recover data.

Step 2: Launch the application and click on the “Hard Drives and Locations” option on the side left panel. Then, choose the drive from where you want to recover data under the “Hard Disk Drives” section.

Step 3: To begin scanning, click the "Start" button at the bottom right corner of the selected drive tab.

Step 4: Wait for the application to scan and recover files from the partition of your Mac. After the scan is completed, you can preview the recovered files to confirm the data is accurate.

Step 5: If all the recovered data is to your satisfaction, click on the “Recover” button to restore lost data.

Step 6: Choose the location to save the recovered data on your Mac. Ensure to select a different location to save recovered data from the original location.

Part 4: Tips to Prevent Restore to Single Partition Issue on Mac

When you are hit with your disk could not be restored to a single partition issue, you can effectively resolve them with solutions now. However, it is better to avoid the issue rather than apply solutions.

Here are the following few tips for you to consider to prevent future single partition issues:

• If your Mac is running an old or outdated version of macOS, you might run into issues such as the disk could not be restored to a single partition. To avoid these concerns, make sure to upgrade your system regularly when available.
• It is recommended to utilize the First Aid feature on Disk Utility regularly rather than when there is a hard drive issue. It will help you in diagnosing the general health of the hard drive and preventing problems before they occur.
• If the disk is full and does not have enough free space, it can create more issues for your Mac. Thus, ensure that a minimum of 20 percent of the hard drive space remains free at all times.
• To properly manage partitions, use Disk Utility to create, delete, and combine partitions. It is recommended to keep the firmware and user data separate partitions to ensure that they are properly organized.
• Alternative to using Disk Utility on your Mac, avoid using random third-party disk management applications to partition the disk. If you want a convenient solution, consider using a legitimate tool that is safe and will not affect your Mac.

Conclusion

There are multiple reasons why you might encounter difficulty when attempting to run Boot Camp Assistant. Perhaps the most prominent causes are insufficient boot disk space or unallocated free space. However, you can easily resolve the issue with the help of easy solutions provided in the article. Nonetheless, it is important you should use Recoverit Data Recovery to recover the data from the partition before proceeding with fixes.