应该是没插好，重插一下呗，也有可能驱动的问题（概率很小）

深度终端里运行命令：

把输出结果贴上来。

ys@As:~$ sudo dmesg | tail -n 20
[sudo] ys 的密码：
[26327.453626] sd 6:0:0:0: [sdc] Sense not available.
[26327.453630] sd 6:0:0:0: [sdc] 0 512-byte logical blocks: (0 B/0 B)
[26327.453656] sd 6:0:0:0: [sdc] Attached SCSI removable disk
[26327.573398] usb 2-1.2.4: new full-speed USB device number 28 using ehci-pci
[26327.682638] usb 2-1.2.4: not running at top speed; connect to a high speed hub
[26327.684175] usb 2-1.2.4: New USB device found, idVendor=0123, idProduct=4567
[26327.684177] usb 2-1.2.4: New USB device strings: Mfr=1, Product=3, SerialNumber=2
[26327.684178] usb 2-1.2.4: Product: USB 2.0 PenDrive
[26327.684179] usb 2-1.2.4: Manufacturer: GENERAL
[26327.684180] usb 2-1.2.4: SerialNumber: 0000000000001378
[26327.684451] usb-storage 2-1.2.4:1.0: USB Mass Storage device detected
[26327.684534] scsi host6: usb-storage 2-1.2.4:1.0
[26328.777382] usb 2-1.2.4: reset full-speed USB device number 28 using ehci-pci
[26328.981426] usb 2-1.2.4: reset full-speed USB device number 28 using ehci-pci
[26329.193393] usb 2-1.2.4: reset full-speed USB device number 28 using ehci-pci
[26329.273400] usb 2-1.2.4: device descriptor read/64, error -32
[26329.877391] usb 2-1.2.4: device not accepting address 28, error -32
[26329.957391] usb 2-1.2.4: reset full-speed USB device number 28 using ehci-pci
[26330.169382] usb 2-1.2.4: reset full-speed USB device number 28 using ehci-pci
[26330.253381] usb 2-1.2.4: device descriptor read/64, error -32

ys@As:~$ sudo lsusb
Bus 002 Device 029: ID 0123:4567  
Bus 002 Device 004: ID 1a2c:2d23 China Resource Semico Co., Ltd
Bus 002 Device 003: ID 1a40:0101 Terminus Technology Inc. Hub
Bus 002 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 003 Device 007: ID 046d:c52f Logitech, Inc. Unifying Receiver
Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 005: ID 04f2:b217 Chicony Electronics Co., Ltd Lenovo Integrated Camera (0.3MP)
Bus 001 Device 004: ID 0a5c:217f Broadcom Corp. BCM2045B (BDC-2.1)
Bus 001 Device 003: ID 147e:2016 Upek Biometric Touchchip/Touchstrip Fingerprint Sensor
Bus 001 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

USB接口有问题，可能是U盘自身的质量不太好。
你在其他电脑上试一试，看看这个U盘能否正常拷贝文件。