Symptoms
- Device doesn't appear in Finder, System Report, or the relevant app
- Device works on other computers but not this Mac
- Device is recognized intermittently or only in certain ports
- A specific type of device (like a card reader or dock) is affected more than others
Likely causes
- CommonA faulty or low-quality USB cableCables, especially cheap or well-worn ones, are a very common failure point.
- CommonUsing a USB hub or dock that isn't providing enough power or a stable connectionPassive hubs especially can cause intermittent recognition issues.
- PossibleThe device needing specific drivers or software not yet installedSome accessories require manufacturer software to be fully recognized.
- PossibleA USB port issue on the MacThis is more likely if multiple different devices all fail in the same specific port.
- PossibleThe device itself being faultyTesting on another computer helps confirm this.
What to do
- Try a different USB cable if the device uses a removable one.
- Plug the device directly into the Mac rather than through a hub or dock, to rule that out as the cause.
- Try a different port on the Mac.
- Test the device on another computer to see if it's recognized there.
- Check if the device requires specific software or drivers, and install them from the manufacturer's site if so.
- Restart the Mac with the device connected.
- Check System Report (Apple menu > About This Mac > System Report > USB) to see if the device is detected at all, even if not fully functional.
- If a specific port consistently fails with multiple known-good devices, that points to a port-specific hardware issue.
Tools and parts
- Known-good USB cable
When to call a pro
If a specific port fails consistently with multiple known-good devices, an Apple-authorized shop can check for a hardware fault with that port.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.