How to fix Toshiba's external hard drive not mounting on Mac?

Toshiba, the giant hard drive manufacturer, has won a vast majority of commendations because its drives are remarkable and excellent at reading and writing data. Users always choose its lineup for backup or file storage on macOS and Windows platforms. 

However, one day, you find the Toshiba hard drive not mounting on the Mac without any clue. That's bad as this trouble results in the inaccessibility of images, documents, presentations, or numbers on the drive. Just like the real scenario below:

I have a Toshiba 2TB External drive which I have used for the past 5 or 6 months to keep copies of my iPhoto Library and my Time Machine backups on. Yesterday, I plugged the drive into the USB slot to find it no longer appeared on the desktop. In Disk Utility, it was not mounted and I cannot do anything but format it which I don't want to do. Any suggestion to fix Toshiba external hard drive not mounting on Mac?

There are sorts of culprits that may lead to the Toshiba hard drive being unmountable on the Mac machine, which will be presented in this post later. Meanwhile, you needn't worry about this trouble as you can find final solutions here! Besides, how to recover lost files from the unmountable Toshiba hard drive is included also.

How to fix Toshiba's external hard drive not mounting on Mac?

Provided that the Toshiba hard drive being unmountable can be caused by sorts of reasons, this post aims at these culprits by providing pertinent solutions. Just read on!

Solution 1: Check the connection

A firm and stable connection is the priority making your hard drive access smooth. Once the Toshiba hard drive gets unmounted, you should check the connection first.

1⃣️ Replace the adapter, reader, or enclosure. Due to the Mac port design, a connection bridge is necessary to connect the hard drive and machine. Just change the adapter, reader, cable, or enclosure to rule out the connection issue.

2⃣️ Insert the Toshiba hard drive into another port or machine. The Toshiba hard drive being unmounted can be caused by the machine also. You just insert it into another port or computer to see if it's the fault of the computer.

Solution 2: Restart the Mac and Reconnect the drive

Sometimes, your Mac falls into strange yet temporary issues with no sign, which even fails to mount your drive! Facing this, you can restart your Mac to terminate the sudden errors, and then reconnect the hard drive:

Safely eject the Toshiba hard drive > click Apple Menu > choose Restart > reconnect the hard drive when the Mac wakes up from the restart. 

If this way makes no sense, keep trying the following ones.

Solution 3: Make the Mac to show up the Toshiba hard drive

Sometimes, it's not the Toshiba hard drive not mounting or showing up but your Mac is set to un-display the connected hard drives on the desktop. You can make a Mac to display the hard drive via Disk Utility or Finder. Here is how:

1⃣️ You can show all devices in Disk Utility provided that some drives might be hidden for no reason: Disk Utility > View > Show All Devices.

2⃣️ Go to Finder Preferences to let the Mac display the connected hard drive:

Step 1: Go to Finder > Preferences > the General tab and select "External disks" to make external hard drives show on the desktop.

Step 2: Go to Finder > Preferences > Sidebar and make sure the "External disks" under Locations is ticked. Then your external hard drive will show up as normal.

Solution 4: Mount the Toshiba drive with iBoysoft Data Recovery Software

You can also try iBoysoft Data Recovery Software to mount the Toshiba external hard drives. It is configured with powerful disk scanning skills and data recovery algorithms, which can scan for all detected hard drives and pave the way for file recovery. 

iBoysoft Data Recovery Software can recover lost data if the external hard drive not mounting, unreadable, corrupted, and inaccessible. It supports to recovery of lost data from APFS, HFS, HFS+, exFAT, and FAT32 drives on macOS Sequoia, Sonoma, Ventura, Monterey, Big Sur, Catalina, Mojave··· and it works fine on M4, M3, M2, M1, M1 Pro, and M1 Max Mac.

Only with the drive being mounted and data at hand, you can dive into the professional methods to terminate the issue of Toshiba not mounting on Mac.

Step 1: Download and install iBoysoft Data Recovery for Mac on Mac.

Step 2: Launch this program. Select the unmountable Toshiba external hard drive (if it shows up in the drive list) and click "Search for Lost Data". The program will start scanning this drive for recoverable files.

Step 3: After the scanning process finishes, you can click the found files and click "Preview" to have a check.

Step 4: Choose what you want to get back and click "Recover".

Step 5: Go through the recovered files and make sure all desired files are back.

With all files at hand, now we can begin resolving the Toshiba hard drive to make it functional. 

Solution 5: Repair unmountable Toshiba external hard drive with Disk Utility

Fortunately, Mac has a built-in repair tool to check and verify minor errors on disks called First Aid. No matter what problems you are meeting on a disk, First Aid always is your first choice to repair it.

Step 1: Launch Disk Utility on your Mac with Spotlight Search.

Step 2: Choose the grayed-out Toshiba external hard drive from the left drive list.

Step 3: Select First Aid in the top center and click Run.

Then, the Disk Utility begins checking the Toshiba hard drive and repairing it to the best of its ability. Once it ends, it will pop up a window telling you. If First Aid fails to repair the Toshiba hard drive, try the method below.

Solution 6: Perform data recovery before reformatting

If Disk Utility cannot repair your disk that is unmountable, the last solution is to reformat the unmountable external hard drive to give it a new file system.

To avoid data loss, you have to recover lost data from the unmountable external hard drive before the formatting.

If your Toshiba's external hard drive is formatted with exFAT, you can read this guide to learn what to do if it's not mounting or showing up on Mac: How to Fix exFAT Drive Not Mounting/Showing Up on Mac?

If the Toshiba external hard drive starts to have mounting issues on macOS Sequoia, this guide will be helpful: Fix External Hard Drive Not Showing Up/Mounting on Mac Sequoia.

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Why does the Toshiba hard drive not mount on Mac?

Exploring the final reasons seems not that important in resolving the trouble, but they probably remind you of the troubleshooter sometimes. So let's figure out what culprits might cause Toshiba external hard drive mounting first:

With these common reasons being gathered, we can resolve the Toshiba hard drive not mounting issue by ruling out them one by one. Apart from that, you can even consider these factors to diagnose the issues of other hard drives not mounting on Mac.

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