Unable to upload sketch to Arduino Uno (SMD) Cant open device "/dev/ttyACM0"

I am running Linux Ubuntu with an Arduino Uno (SMD)
I am getting this error when I try to upload.

avrdude: ser_open(): can’t open device “/dev/ttyACM0”: Permission denied

I have done this to try to resolve:

sudo adduser dialout
sudo usermod -a -G tty
sudo chmod a+rw /dev/ttyACM0

logged out and logged back in

sudo usermod -a -G dialout <username>

If all else fails, try this article.

Thank you all. I will try these tonight and report back.

I tried the command below and there is an ACM0, but stuck beyond that. I logged out and back in and still nothing. I'm a member of the "Dialout" group as well.

Like the article suggests, to check for ModemManager and serial-Getty, but I dont see those services running.

I dont know how to proceed further.

ls -l /dev/ttyACM* /dev/ttyUSB*
ls: cannot access '/dev/ttyUSB*': No such file or directory
crw-rw---- 1 root dialout 166, 0 Jul 21 21:33 /dev/ttyACM0

"lsusb" command results:

Bus 001 Device 004: ID 1bcf:28ae Sunplus Innovation Technology Inc. Laptop Integrated Webcam HD
Bus 001 Device 003: ID 0a5c:216f Broadcom Corp. BCM20702A0 Bluetooth
Bus 001 Device 002: ID 8087:8001 Intel Corp. 
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 003 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 002 Device 002: ID 0a5c:5800 Broadcom Corp. BCM5880 Secure Applications Processor
Bus 002 Device 010: ID 2341:0001 Arduino SA Uno (CDC ACM)
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

"Dialout"

Dialout or dialout? You need "dialout". Or is that a typo?

IDE version? I used 1.8.5 installed from https://www.arduino.cc/en/Main/Software.

Can you open /dev/ttyACM0 using minicom, picocom, or screen?

Try running ./arduino as root.

I have Arduino 1.6.10

Yes, member of "dialout", typo.

FWIW, I just installed the same IDE version on a Lubuntu 18.04 laptop from the downloaded .tgz file.
I had to run ./install twice (there was an error about the icon directory the first time) then 'sudo usermod -a -G dialout $USER' (no quotes)

Worked perfectly.

Oh goodNESS.

I just DL'd the IDE 1.8.5 and it works perfect. Sorry all, I should have installed that to begin with.
Thanks all for the help.

now the big question is how do I UNinstall the older 1.6.10 version from the terminal?

mryczx:
now the big question is how do I UNinstall the older 1.6.10 version from the terminal?

See if you can uninstall 1.6.10 using Synaptic Software Manager.