Interestingly, after connecting a different external USB storage dock (this time it is USB 2.0) to the internal USB connector of the PCIe expansion card (the internal connector is connected to a front USB connection panel) I don't see the same error. But this time the USB mode used is not uas, but usb-storage. [43128.072163] usb 3-1: new high-speed USB device number 2 using xhci_hcd [43128.193393] usb 3-1: New USB device found, idVendor=04cf, idProduct=8818 [43128.193397] usb 3-1: New USB device strings: Mfr=1, Product=2, SerialNumber=0 [43128.193398] usb 3-1: Product: USB Mass Storage Device [43128.193399] usb 3-1: Manufacturer: Myson Century, Inc. [43128.195546] usb-storage 3-1:1.0: USB Mass Storage device detected [43128.200860] scsi host12: usb-storage 3-1:1.0 [43129.205168] scsi 12:0:0:0: Direct-Access SAMSUNG SP0411N TW10 PQ: 0 ANSI: 0 CCS [43129.205599] sd 12:0:0:0: [sdg] 78242976 512-byte logical blocks: (40.0 GB/37.3 GiB) [43129.205766] sd 12:0:0:0: [sdg] Write Protect is off [43129.205768] sd 12:0:0:0: [sdg] Mode Sense: 00 14 00 00 [43129.205891] sd 12:0:0:0: [sdg] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA [43129.207278] sd 12:0:0:0: Attached scsi generic sg7 type 0 [43129.231780] sdg: sdg1 sdg2 < sdg5 > [43129.232631] sd 12:0:0:0: [sdg] Attached SCSI disk So maybe this is only a bug when uas is used? -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html