Serial Port greyed out Ubuntu 16.04 I am running Ubuntu Mate 16.04 LTS, with an Arduino Uno R3 clone. I am having the dreaded serial port graying out problem, and have not found a solution for fixing it. Currently, The serial port will grey out sometimes, and sometimes it will be not grayed out, and I can see that I have selected ttyUSB0. Usually when it is not grayed out, uploading a sketch will not work, and I get the error like it is grayed out:


  avrdude: ser_open(): can't open device "/dev/ttyUSB0": No such file or directory
  An error occurred while uploading the sketch


chmod a+rw /dev/ttyUSB0


doesn't solve the issue, with log out included

gpasswd -a aaron dialout


doesn't solve the issue, with log out included

I searched preferences.txt and serial.debug rate is set to 9600

I have tried entering preferences.txt and deleting all of the serial entries. They are recreated the same after deletion, and this doesn't solve anything.

I tried running as sudo, doesn't work.

I tried solving this originally on Arduino IDE 1.0, didn't work.

I have upgraded to Arduino IDE 1.6.10, still not working.

running lsusb in terminal yields this while Arduino is plugged in:

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 001 Device 003: ID 0a5c:21e6 Broadcom Corp. BCM20702 Bluetooth 4.0 [ThinkPad]
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
Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub


Checking var/log/syslog after plugging in Arduino:


  kernel: [42043.787178] usb 3-2: new full-speed USB device number 109 using xhci_hcd
  
  kernel: [42043.916241] usb 3-2: New USB device found, idVendor=1a86, idProduct=7523
  
  kernel: [42043.916249] usb 3-2: New USB device strings: Mfr=0, Product=2, SerialNumber=0
  
  kernel: [42043.916253] usb 3-2: Product: USB2.0-Serial
  
  kernel: [42043.916964] ch341 3-2:1.0: ch341-uart converter detected
  
  kernel: [42043.918199] usb 3-2: ch341-uart converter now attached to ttyUSB0
  
  mtp-probe: checking bus 3, device 109: "/sys/devices/pci0000:00/0000:00:14.0
  /usb3/3-2"
  
  mtp-probe: bus: 3, device: 109 was not an MTP device


Ran to add to dialout group, then logged out

sudo usermod -a -G dialout aaron


No solution.
So it looks like Arduino board is not being recognized. Not sure what to try next. It is important that I have uploaded sketches before, but am not sure if there is a pattern to when it does not work. It does not work 95% of the time.

Thanks for the help!
I have the same problem, 
I believe that the problem is related to the 4.x kernel, since I have already tried another distribution with the kernel mermo and the problem persists. Using a windows virtual machine as guest works, which excludes communications and hardware issues.