The Problem

You want to access ubuntu server with its graphical user interface you install TightVNC or x2go. I installed TightVNC's vncserver in my Ubuntu and was able to access it for a few days and then suddenly saw this: "Authentication reason: Too many authentication failures". That drove me nuts and wouldn't let me in.

The problem may occur by you, making too many failed attempts to login to vncserver, or it can be bots accessing your server with brute force methods.

The Solution:

You will have to kill the vnc process and restart it to gain access to the vncserver again. Connect to your server via ssh and run the following command

pgrep vnc

// the output will look like following but yours will be different (sure thing)
17732
23723

You will see one or more process ids that are running against vncserver. Just run the following command for each process id

kill PID

// In my case I ran the following two since I had two process ids
kill 17732
kill 23723

Now you have killed TightVNC on your Ubuntu. Turn it on again and you'll be fine to connect again. To make the VNC up and running again, run the following command.

vncserver -geometry 1920x1080

That's it!

TightVNC working again on my server:

Further, read on how to prevent this from happening again can be found here by solveopti.

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