[Solved] Mac Not Recognizing USB

By Nicholas J. Johnson | October 14, 2019

Are you Mac not recognizing the USB device you connect to it? This issue often appears due to some internal software or hardware glitches, like when the USB port of Mac malfunctions.

Apart from that, if the external disk preference within the ‘Finder’ application is not set correctly, then also you can face this problem. The Mac may not recognize the USB device if the USB flash drive itself does not perform as it should.

Further, if the SMC settings of the Mac gets corrupted somehow, then this problem might crop up. Another probable reason for this issue is an outdated macOS.

Whatever the reason is, fortunately, there are solutions to fix this issue and that is what we are going to discuss here. So, follow this article to the end and apply the fixes provided to get rid of this error in no time.

USB Device Not Recognized by Mac: Fixes to Try

Mac unable to recognize a USB device can be due to several reasons as stated above. The following fixes will help you resolve this issue no matter what the cause is. So, follow and apply them one by one until the issue resolves.

1: Reset the USB Ports of the Mac

If the USB Ports are not functioning properly, then you can face this error. Now, the best answer to resolve this issue is to reset the USB ports of your Mac. Here are the steps to do it correctly:

First, reboot the Mac computer by clicking the ‘Apple’ logo on the upper left corner of the screen and then choose the ‘Restart’ option.
As soon as the machine restarts, immediately hit the keys ‘Command + Option + P + R’ and hold them until the ‘Apple’ logo comes up.
When the desktop appears, press the keys ‘Command + Option + Esc’ together to quit every program that is not responding.
Now, insert the USB device that the Mac does not recognize. If the USB device is still not shown, tap on the ‘Apple’ icon and choose the ‘Sleep’ option.
Once you have done that, after a couple of seconds, wake the machine up by pressing any key.
At last, switch off the computer and disconnect the power cable, and then after fifteen seconds boot the Mac and see if this issue reappears or not.

2: Use the First Aid Tool to Repair Problematic USB Flash Drive

If the USB device itself has any kind of problem, then there is a chance for you to face this issue. You can use the ‘First Aid’ tool to rectify the problematic USB flash drive.

To do that, follow the steps below.

First, from the ‘Dock’ locate and choose the ‘Applications’ folder. As soon as the new window having the heading ‘Applications’ comes up, then from the list of softwares present within the computer, choose the ‘Utilities’ option.
Once you click on that option, a list full of system tools will come up in a new window that has the name ‘Utilities’.
Now, from that window, locate and choose the ‘Disk Utility’ option. This action will launch a new window with the heading ‘Disk Utility’.
Within this window, go to the left pane and choose ‘USB flash drive’. After that, go to the upper section of that window and click on the ‘First Aid’ button.
If a confirmation message box comes up, click on the ‘Run’ button to check for any issues with the USB flash drive and fix them automatically.
Once the checking process is complete, choose the USB device from the ‘Disk Utility’ window once more and click on the ‘Unmount’ button.
Finally, remove the USB device from the Mac and after ten to fifteen seconds connect the drive and see if this issue is fixed or not.

3: Inspect and Correct Any Glitches in USB using Terminal

Here you will get to learn the method to identify and rectify any problems in relation to the USB devices using the Terminal application.

First, click anywhere on the desktop wallpaper.
After that, navigate to the top section of the screen and choose the ‘Go’ option. As soon as you click on that, a drop-down list will appear.
Next, from that list, locate and choose the ‘Utilities’ option. Now, a new window having the heading ‘Utilities’ will come up.
Now, from that window, scroll down a little then find and double-click on the ‘Terminal’ option. When a new ‘Terminal’ window comes up, type the command – “diskutil list” and hit the ‘Return’ button.
Now, from the list of disks presently connected to the computer, locate the disk number of the USB drive and enter the command – “diskutil info disk2” and press the ‘Return’ button to execute. In this command, replace ‘2’ with the valid disk number of the USB drive.
Once the execution of the above command is complete, next, type another command ‘diskutil eject disk2’ and tap ‘Return’.
Next, again type the command “diskutil list” and press the ‘Return’ button. If the USB drive is not present within the list, close the ‘Terminal’ window and launch the ‘Console.’
Inside the ‘Console’ window, click on the ‘Errors and Faults’ option to check for any errors with the USB drive.
At last, disconnect the USB drive and after sometime reconnect it to see if it gets detected or not.

4: Reset the PRAM

The Parameter random access memory or PRAM contains data regarding the USB devices. Now, the best answer to resolve this problem is to reset the PRAM. For that, follow the steps below.

First, shut down the Mac computer properly.
Next, start the device once again and then immediately press the four keys – “Command + Option + P + R” altogether until you hear a chime and see a flash on the screen.
Once you hear a chime, next, allow the Mac computer to boot normally.

5: Reconfigure the SMC

If the System Management Controller settings get corrupted somehow, then also the Mac may not be able to recognize the USB device. The correct answer to get rid of this problem is to configure the SMC once again.

Follow these steps to reset the SMC on a MacBook:

First, turn off the MacBook machine. After that, insert one end of the power adapter to the MacBook and the other end to the wall socket.
Next, press the keys ‘Shift + Control + Option + Power’ simultaneously for two seconds.
After 2 seconds, let go of all the four keys at the same time.
Lastly, boot the MacBook normally and see if this issue comes up or not when you insert any USB drive into the machine.

The reset process of SMC for to Mac mini, Mac Pro, iMac is as follows:

First, shut down the Mac computer. Next, remove the power cable from the wall socket.
After that, press the ‘Power’ button of the device and hold it for five seconds. Next, release the button.
Finally, connect the power cable back into the wall socket and start the Mac to see if this problem is fixed or not.

6: Update the macOS

If the macOS is not up to date, then also you can face this error. Performing an update of the macOS can resolve this issue of Mac not recognizing USB. The steps to do that are as follows:

First, go to the upper left corner of the screen and then click the ‘Apple’ logo.
As soon as you click on that logo, a drop-down list will appear.
Now, from that list, locate and choose the ‘System Preferences’ option. When you click on that option, a new window having the name ‘System Preferences’ will come up.
Next, from that window, locate and click on the ‘Software Update’ button.
At last, wait for the OS to check for an update. If an update is found, then that will be downloaded and installed automatically.

Mac not recognizing the USB can be solved easily if you follow the methods given above carefully. You can mention in the comments which of the fixes worked for you.

Posted in Mac