USB Accessories Disabled

[CronoCX]

Hey!

So, I've been trying to trace this error down for a while and I was hoping this App could help and maybe someone can explain it to me. So, I have a CalDigit TB5 Plus dock and it's been great, but every now and then, I'll get this error:

Since macOS does not give me any more information, I check all my connections, and all of them continue to work perfectly fine. My TM Drive stays mounted, my iPad remains charging, it's weird. It's VERY possible this is just a bug in macOS Sequoia, but if there's a way for the App to help track things down, suggestions would be appreciated!

--Brian

PS: My older CalDigit TB 3 Dock never had an issue like this.

[CronoCX]

Followup: I've sent an email to CalDigit Support to ask them. I also included a bunch of screen shots of What Cable in terms of what it sees with their cable, which is fine. We'll see what they say.

I also turned on tracking for the cable to the dock. I know from another thread your working on being able to track cables which use Hubs, that'll be most helpful too.

--Brian

[darrylmorley]

Hi Brian,

That "USB Accessories Disabled" notice is macOS's over-current warning, not a cable or data fault. macOS briefly cuts power to one of the dock's downstream USB ports because a device pulled a short current spike (inrush when something wakes or spins up). It's transient, so the port comes right back and nothing actually drops, which matches what you're seeing. That's also why WhatCable shows the TB5 cable as fine: it's happening on the dock's downstream USB rails, not on the link to your Mac. Your TB3 dock likely had a more forgiving power budget, so it never tripped.

Next time it fires, note if it lines up with a specific device waking or a bus-powered drive spinning up, that's usually the culprit (a self-powered device rarely is).

On our side, the one thing WhatCable might catch is a port reset on the Mac's own port. If the notice ever coincides with that, it's a real lead. If not, the event lives entirely inside the dock, where macOS doesn't give us the downstream power data.

Curious what CalDigit say. Keep us posted.

[CronoCX]

So far it's been random, like powering AirPods, or connecting an older USB Stick....things that I would not expect to trip it. I'm usually really OCD about patterns and will ADHD for hours tracking them, but so far, I haven't found one.

[CronoCX]

Hey Darryl,

I just wanted to say how much I appreciate you taking the time to talk through what I was seeing like a human and in a positive manor. You have my upmost respect :-) I've been doing computers since I was like 6, all the back to the Apple IIgs and I like to think I can dig into things, but my knowledge hits a wall sometimes.

I will absolutely keep you posted. I am now super interested to hear what they say too. (I think I remember this being a macOS bug in Tahoe, maybe here too, we'll see. That's what I'm guessing it is, but the cable was my starting point...which took me to your App and this exchange :-D)

--Brian

[CronoCX]

Hey!

First, Darryl! Thought you’d like to know that CalDigit Support LOVES your App :-) And now I have an update for this case!

For the past few days, myself and a CalDigit Support Rap have been tracking this issue down. In my initial email I sent them all the info I had, including a wiring diagram to indicate that I did not think it was a bandwidth issue. The TB5 Plus Dock has TWO Controllers in it, which is why it can deal with so many devices. They have a diagram on their website saying which port is what Controller too. But I wanted them to know how my wiring was setup. I also included some screenshots of WhatCable and what it was telling me. I also sent them a System Diagram so they could dig through that.

They first came back with it was most likely an iOS Device, which would line up as to the device that was connected with the Cable I thought might be causing an issue. They also recommended updating the PD Firmware as that had a new version, which I did.

“This looks like the USB/Thunderbolt port identifier can’t be recognized, the device is disconnecting and reconnecting rapidly, and your system is giving it a new number or treating it as a new device each time it happens. It might mean whatever device you have isn’t completing its Thunderbolt/USB handshake correctly.

You could be getting the notification because an attached iOS device is connecting intermittently, there’s a faulty cable, or a power delivery conflict.

You can try disconnecting all iOS devices from your system (including any you might have connected wirelessly). If the issue stops, that probably confirms the culprit. “ - CalDigit Support

But after doing that, since I knew I’d have more data if I connected directly to my Mac and gave it a label. What happened next was interesting, when I disconnected and reconnected, that label was gone. I then gave it a name again to monitor that activity. But that would track with what Support said about macOS treating it as a new device.

Screenshot 01

Screenshot 02

Screenshot 03

Of course once I connected this cable, which was from Nomad, we see a lot of more information about it, including my new favorite thing, drop rates!

Screenshot 04

Screenshot 05

My current hypothesis, and waiting to see what Support says, is that WhatCable correctly identifies this as a USB2 speed cable, which it is, this Cable is not meant for data and I’m using it as a charge cable, but putting it into a dock or computer might not be the best use for it because the Mac and Dock are expecting more from it then it can give, thus showing up like it does in the above Screenshots. That said though, speaking of the Screenshots, I think there’s some room for better language or illustration here in the orange “Connection” section. Specially Screenshot 04, “without you touching the cable” is wrong. All of those were me disconnecting it from the iPad. The only way that alert does NOT come up is if you eject the device first. iOS devices for some reason I never eject, but I do for everything else.

That should be noted somewhere. It should also be suggested that your cable might be fine, it’s just not built to deal with high speed data, which it kind of does, but the majority of this alert is saying the cable or port are bad, but that might not be the case.

Separate from that, and more interesting is Screenshot 05, in those connection alerts, I did NOT touch the cable at all. At this point, what Darryl said about the “USB Accessories Disabled” error was not a cable alert, but an over-current warning. It could be that when waking the iPad, that caused a spike in power draw or something. All of that said, I do think that this cable is actually bad, just based on how it performed in the other tests.

—Brian

[darrylmorley]

Hi Brian,

Sorry for the slow reply, I've been buried in WhatCable work. Cracking bit of testing though, and you've found a real one.

You're right about "without you touching the cable." That number comes from a connect/disconnect tally your Mac's port controller keeps. It's a real hardware signal, but on its own it can't tell who caused a change, or which end of the cable it happened at. Unplugging the iPad at the far end (without ejecting first) looks identical to a drop from where it sits, so the tally ticks and the banner overstates its case. Two fixes coming: that line goes, and over the next couple of releases the banner will cross-check the app's other readings (speed, resistance, power) before it calls anything a fault, so it stays quiet when you're just unplugging a device.

Two alerts worth keeping separate, since they're easy to mix up:

• macOS "USB Accessories Disabled" is a power warning, something on the dock briefly drew too much current and the dock cut that port. That's happening inside the dock, a step removed from the cable up to your Mac.
• WhatCable's orange "connection dropped" banner is about connect/disconnect events, nothing to do with power.

CalDigit's "device re-handshaking" idea is about the second, not the first.

On the label dropping off: if a cable's chip carries a unique ID, WhatCable can recognise it anywhere, but plenty of charge cables don't, so it can only follow those while they stay on one port. The on-screen note should say that plainly, and it will.

And the cable itself: USB 2.0 just means slow, not faulty. But a cheap charge cable can still be electrically marginal, and your shot with drops when you didn't touch it is fair reason to suspect this one. If you've a spare, a swap will settle it.

Thanks again.

--Darryl

[CronoCX]

Thanks for this!

[darrylmorley]

Hi Brian,

A follow-up with something useful. I dug into the downstream side and confirmed macOS does expose a per-downstream-port overcurrent counter on the dock, which I'd assumed we couldn't see. If it reliably catches these trips (and your dock is exactly the thing to prove that on), a future WhatCable update could point at the specific dock port that tripped instead of leaving you guessing.

I'll follow up here when there's something to test. Thanks again for the report, it sent me somewhere genuinely worthwhile.

[CronoCX]

That sounds like it would be a cool feature!