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macrumors bot
Original poster
Apr 12, 2001

MacBook Air and MacBook Pro owners who have one of the new 13-inch 2020 models released earlier this year appear to be experiencing problems with USB 2.0 accessories that connect to their machines though a hub or adapter.


There are a number of complaints about the issue on the MacRumors forums, Reddit, and the Apple Support Communities. Affected customers appear to be seeing devices connected to the Mac randomly disconnect, as explained below by a MacRumors reader.
At random times the USB devices connected to the mac though a usb-c hub would just lose connection and stop working all at the same time. This happened with two different USB-C hubs (both expensive, one of them is Satechi which was recommended in many threads), so I am leaning towards ruling out the hubs being at fault.

I'm connecting a few things in the hub - HDMI for an an external monitor, USB audio interface (powered by the mac) and a mouse. When the issue occurs, the mouse and the USB audio interface stop working, but the HDMI connection continues to work without issues, each time.

The issue happens at random moments and there are no steps to reproduce it. It seems to be happening more often when at least two usb devices are connected at the same time.
There are many other similar complaints about disconnection and freezing issues when using USB 2.0 accessories that connect to a Mac through a hub, though there seems to be no clear pattern as to which accessories are affected or when the issue occurs, making it difficult to determine what could be causing the disconnects.

MacBook owners have run into connectivity problems with all kinds of devices that require a USB-A connection, including mice, keyboards, and other accessories. Multiple hubs have been tested, which suggests that the issue is not caused by a particular brand of hub, and it also appears that most of the complaints are limited to USB 2.0 accessories rather than USB 3.0 and 3.1 accessories.

SMC resets, safe mode, Disk Utility repairs, different user logins, and operating system reinstalls have all been unsuccessful addressing the bug, which suggests that it may be something that Apple needs to fix in a future software update, if it is a software problem.

A Reddit user found that USB 2.0 devices that become unresponsive remain indefinitely in the System Information even if unplugged from a hub, while USB 3.0 devices behave properly, so this is one possible cause. He was able to solve the problem with a Thunderbolt CalDigit hub, but whether that fix will work for all impacted machines is unknown, and CalDigit Thunderbolt hubs are pricey.
Apple has a USB 2.0 issue with either the chipset they are using, or a Catalina bug regarding the handling and refreshing of USB 2.0 devices.

However this can be worked around.

USB-C hubs vary in their functionality and there are two types:

1. USB hubs that are transparent proxies
- The Anker, Satechi and StarTech hubs
2. USB hubs that are terminating proxies
- The CalDigit hub and anonymous person on the internet and their monitor hub

Transparent proxies take the USB 2.0 input and present it as USB 2.0 to the MacBook Pro. The Mac or Catalina then will do something wrong and the USB 2.0 devices will freeze / become unresponsive at some point (minutes or hours after being attached).

Terminating proxies take the USB 2.0 input, terminate it, and present it as a fresh input that is USB 3.0 to the MacBook Pro. Everything is good in this scenario.
Multiple MacBook Pro and MacBook Air owners have contacted Apple so Apple may be aware of the issue and could have a fix in the works. Apple has been replacing some affected machines with new models, but users report that the problem persists even when a new Mac is provided.

Article Link: Some 2020 MacBook Pro and MacBook Air Users Experiencing Issues With USB 2.0 Accessories
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macrumors 6502
Jul 9, 2015
I have this problem with my 2020 MBA, which I did not have with my 2019 MBA. My solution, as stated in the post, was to get a Thunderbolt dock (I got the Belkin Mini, but Thunderbolt docks are expensive especially compared to USB-C hubs). Triggered by just having my USB mouse and keyboard plugged in, with no solution except rebooting.
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macrumors regular
Sep 17, 2019
Is this issue restricted to 2019/2020 models? That is when Apple switched from the Intel Alpine Ridge TB3 controller (which also handles USB) to the newer Titan Ridge controller. Anyone reporting it on a 2019 iMac (which also has a TR controller)?

Not sure about everyone else but my USB hub works great with a 2019 MBP I have but isn't recognized at all with the new 10th Gen. MBP


macrumors 601
Dec 15, 2010
I am not having any issues and have connected a number of devices to my MacBook Pro using the USB adaptor. CD/DVD Drive, camera, camcorder, Garmin GPS, voice recorder, etc..
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macrumors 6502a
May 6, 2006
Leeds, UK
Huh I guess this might explain why I’ve been having problems with a Kensington Slimblade and my new MacBook Air. It works fine if connected with a simple usb a-c adapter but has weird issues if connected via a hub.


macrumors 68040
Oct 3, 2009
Not necessarily relevant, but my experience with my 16 inch MBP is that the cheapest no-brand USB-C to USB 3.0 adapters work 100% of the time while my expensive Satechi hub works 90% of the time. More expensive doesn't necessarily mean better.

That said, I do very much miss the USB-A ports. USB-C has been "the future" for many years and it's still pretty much non-existent unless you're buying some high-end needlessly expensive designed-for-Mac accessory that comes in rose gold.

Depending on what you do, you can likely live without any form of Ethernet, floppies and CDs but there's no way around USB-A for the foreseeable future.


macrumors newbie
Aug 2, 2010
I'm actually having USB 3.0 issues when using the Elgato Camlink 4K & Apple USB C adapter. I have reset SMC all the time to have the Camlink work. This is 2020 MBP 16.
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macrumors regular
Jun 16, 2009
I'm on a 2019 16" MBP, and this has been happening to me since 10.15.4; clamshell no longer functions whatsoever, and my Bose USB 2.0 speakers drop ALL the time.
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macrumors 68020
Oct 14, 2005
Interesting. Working from home I’ve had my MBP plugged into a TB3 monitor that also works as a USB hub. Only device I’ve had continually connected is my Time Machine drive, and that’s via USB-C/3. I’ve had a handful of spontaneous restarts, but only when the machine has been left alone for a long period; never while using.

Until today. Repeated kernel panics and restarts. Clean installed the OS and it’s been stable since, but I’ve been using my Time Machine external directly connected instead of through the monitor. About to set up my Raspberry Pi as a wireless TM backup, but interested to see if a fix comes out for this.


macrumors newbie
Jun 7, 2020
Got the same issue on my 2020 Air. It's only one of them (the top) that stops working and then suddenly starts working again. This applies to both USB C and USB A (dongle) devices. And like it said in the article even when removed, it still shows up in the system information.
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