USB drive doesn't mount for a first time

I also have this problem plus once mounted it will eject itself halfway through being written too. I have to do it in parts which is a pain when part of my job involves me putting around 2000 photos on USB regularly!

I've tried restarting, taking everything else out that is plugged in.. can't think of anything else to try.

My external hard drives are fine though.

I also have this issue with any USB drive or SD card. I do not, nor have I ever had VMware like the others mention in this thread. The issue has been occurring since day 1 on my MacBook Pro 15" Aluminum unibody (Mid 2010), which I believe came with Leopard, continued with Snow Leopard (Clean Install), through the various OS versions since then, several hard drive replacements later (clean install of OS every time), and still occurs with Mavericks and El Capitan (again, always a clean install). It was not annoying enough to send my computer in to Apple under warranty and have downtime. Around the year 2016, the logic board failed, resulting in intermittent video output issues. I paid Apple to replace it since I would rather spend an unlimited amount of money in repairs on a laptop that has a Matte screen versus a new one since Apple discontinued the Matte screen option. The issue still occurs, so replacement of the logic board does not resolve this. Please, apple, look into this software issue plaguing many customers!

Hello Sashokus,

After reviewing your post, It sounds like a USB drive is not being recognized when you connect it to the computer. It looks like you have already done some troubleshooting. I would recommend you read this article, it may be able to help troubleshoot the issue.

OS X El Capitan: If a USB device isn’t working

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Thank you for using the Apple Support Community. Due to the nature of your issue you may find more information by using another one of Apple's support resources - https://expresslane.apple.com/GetproductgroupList.action

For what it is worth, I am experiencing the same thing.

Same problem here. Maybe relating to wmware fusion?

I've had this problem since El Capitan released. I keep hoping for an OS patch to address this. It affects all of my USB devices including drives, thumbdrives, etc. Doesn't matter what order connected. Hardware bus reset, etc. do not help. Because the workaround works reliably, I don't want to send my MBP Retina in for service and have any downtime.

Anyone ever received resolution for this issue? I have the same using an iMac Retina with OS X 10.11.4. No USB-connected device (thumb drives, external drives, iPhones and iPads) is recognized on the first connection; must connect twice. At first this was merely annoying but when my phone tried to upgrade while connected it became a real issue since the connection is dropped during the process (I had to pull out my old MacBook and restore from there).

There doesn't seem to be much on this issue but I DID see this problem surface on a VMWare support forum. I do use VMWare on this machine, and although I am not trying to use USB devices with any virtual machines - VMWare is present, so I wonder if this is the common thread here?

I also have VMWare fusion installed, version 7, latest release. I went ahead and paid to upgrade to version 8 today (earth day sale at the moment...) and immediately after upgrading the USB-problem went away for me. I have always had to consistently plug things in twice for all USB devices and drives. Now I can just plug them in once and things are working. Hope this helps someone else.

I concur that VMWare is the culprit ... I'm only on VMW 6, but just found if I simply shut down the VM and quit the app - USB functions as it should. Since I only need the VM occasionally for one app, this is not a problem.

I've got the same situation. Do you open the VMWare when you connect to the USB?

In my case, if I don't run VMWare, USB is okay.

The problem is: after running VMWare and plug the USB, VMWare asked me where to connect "Windows or Mac" as this is my prefer setting for USB in VMWare. Whatever I chose, it doesn't show it in the Windows or Mac. *** if the HDD format is Mac OS Extended ***

In the VMFunsion7, Windows 7, I installed USB2.0 driver and WD SES Driver Setup (x86). Then HDD Format is NTFS, it's working.

I just stopped leaving VMWare running all the time, and all is fine with the USBs again. For the few occasions I need a Windows VM I start it up, do what I need and shut it down again. I've never needed to attach a USB device to my VM so that was not an issue for me.

Same problem here. For a long time now (probably since the upgrade to El Capitain) I've had to plug every USB thumb drive and every SD-card twice. Upgrading to Sierra didn't solve the problem. Unlike many others in this thread, I've never used VMWare. AND this problem occurs both on my MacBook Pro and my iMac.

This happens all the time on my 13" Retina 2015 (Sierra).

Has anybody found a solution?

Please Apple fix it, it's so annoying.