When connecting from Windows to my Linux box using MobaXterm, I cannot open Linux-GUI applications on the Windows side. On the Windows side, nothing happens. On the Linux box I get this error message:

MobaXterm X11 proxy: Unsupported authorisation protocol
** ([program]:[processId]): WARNING **: Could not open display localhost:10.0

4 Answers 4


In my case, the problem was a missing entry in ~/.Xautority on the Linux machine. You probably shouldn't edit the file directly, but use the commandline tool xauth.

Take the display name and the id from the error message and use them in the xauth command.

Could not open display localhost:10.0
                       ````````` ``

In my case it's localhost and 10. To add it, use the xauth add command:

xauth add localhost/unix:10 MIT-MAGIC-COOKIE-1 27e035688dd89483c6fe48b2470172f5
          `````````      `` 

The last hex-number is 32 characters long. You can create your own (quite) random number on the Linux shell with one of these commands:


uuidgen -r | sed s/-//g

head -c 16 /dev/urandom | xxd -p

You can check, what has been added by command xauth list.


I had this problem running firefox. It turns out that I had the snap version installed (according to which firefox). I installed the apt version with

sudo apt install firefox

and now firefox launches Firefox over MobaXterm just fine.


TL;DR version: type:

xauth add :0 . `mcookie`

I had exactly the same error. Turned out that the disk quotum of the user reached it's end and there was no space left for the .Xauthority file.

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .