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New iMac disconnecting drives on USB C constantly

Cannot keep a drive, any drive, connected on USB C ports - constant disconnections and crashes. This happens on powered hubs, direct connections, both USB C ports do the same and can find no hardware issues, machine passes diagnostics no errors found, drives are APFS and Exfat

iMac Line (2012 and Later)

Posted on Nov 13, 2021 10:17 PM

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Posted on Nov 14, 2021 11:58 AM

Disconnect the hub and the external HDs and troubleshoot as I recommended. it is not uncommon for external peripherals (including USB hubs) to cause issues. If the USB does NOT have it's own power supply that is also and issue, all hubs and docks should have their own power supply and SHOULD NOT be bus powered.

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Question marked as Top-ranking reply

Nov 14, 2021 11:58 AM in response to monkeycnet

Disconnect the hub and the external HDs and troubleshoot as I recommended. it is not uncommon for external peripherals (including USB hubs) to cause issues. If the USB does NOT have it's own power supply that is also and issue, all hubs and docks should have their own power supply and SHOULD NOT be bus powered.

Nov 13, 2021 10:51 PM in response to monkeycnet

Please navigate to www.Etrecheck.com and download the free version of EtreCheck. Once you have you downloaded the app and installed it, please run the report and save it. This report will help us get a good idea what has been installed on your system and help us be able to diagnose what may be wrong.


When you have your report, you can attach it when you reply to this message and we can then review it and help you determine what is needed to get your system running well again. 


For instructions on how to download your EtreCheck report and attach it to your reply to this message please click https://discussions.apple.com/docs/DOC-250000211


Nov 14, 2021 10:39 AM in response to rkaufmann87

I have 2 HDDs connected. A 500Gb Seagate SD and a 1tb Lacie HDD for time machine. I have tested with multiple other drives and problem exists with them all.;


All other devices are on powered USB hub and include a printer and some lights and thats it. This is exactly the same config as my 21.5 iMac that this one replaced and had no issues on that system

Nov 15, 2021 11:32 AM in response to rkaufmann87

Im doing this- however i will note that my usb hub is an expensive powered one and i have had issues with four drives that work fine on the 3 other macs in the house, the only one i have issues with is the brand new imac. The exact same devices were plugged into my older imac with no issues at all. I do not believe this issue is drive related

New iMac disconnecting drives on USB C constantly

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