Error message: Can't connect to x11 window server


Hello, I"m using the mBlock 3 chrome OS app for my chromebook. It was working well for me and I was able to upload yesterday but when I upload to my mBot today I get an error when it compiles.

Exeption in thread “main” java.awt.AWTError: Can’t connect to x11 window server using ‘:1.0’ as the value of the DISPLAY variable
at sun.awt.x11GraphicsEnvironment.iniDisplay(Native Methd) …

Here is a video of my error.

Please Help!


I think this is happening worldwide for Chrome and any browser development. I see the same thing on Chrome and on my Mac. I had a class full of students today very unhappy that they could not compile their programs. Took me a while to figure out what the issue was. I think it has been a problem for a few days now.

Can someone at Makeblock let us know when this will be fixed? My whole class is designed around Makeblock and being able to use it with Chrome.



Could you post the video again as I cannot open it.
Or please send me a screen shot of the error page, we’ll have a check.


Ok, here is the video. I hope it works this time.
Here is a video of my errow.


It didn’t seem to work I’ll try it again a different way. Here is a video of my errow.


Thanks for the detailed info, Jayson.
I also have same issue like yours, and our software team are checking and trying to fix it. Any update, I will let you know.

Also, I may suggest you to try mBlock 5 web version (mLink):
Or download the mBlock3 software instead of web version.


Thanks for the feedback.
Chrome version issue/mblock 3 web version, we are checking and trying to fix it, will let you then.
mBlock 5 now also have web version (mLink):


Thank you for that option but the mBlock 5 web version (mLink) doesn’t work on a chromebook because it needs the drivers to be installed, unless I"m doing something wrong.


I would love to use Mblock 5. But I have a huge investment in Orion boards and Mblock 5 does not support that board.


Fixed. You can continue to use that.


It’s back: “

I really hope you are able to fix it as fast as you did last time


Sorry for the problem caused. We are checking and fixing it now. If your board is supported by mBlock 5, please try mBlock 5 online version.


Thank you for your quick response.