QXcbConnection: Could not connect to display :0 (solved)

[houmingc]

I cannot start QTcreator
@
under /opt/Qt/Tools/QtCreator/bin
./qtcreator
Error: could not initialize GLX
Aborted (core dumped)

when i sudo su
under /opt/Qt/Tools/QtCreator/bin
sudo ./qtcreator
No protocol specified
QXcbConnection: Could not connect to display :0
Aborted (core dumped)

Answer is in the link below
https://harishnavnit.wordpress.com/2014/03/06/removing-nvidia-x-drivers-to-solve-the-glx-error/

[andreyc]

[quote author="houmingc" date="1420514021"]I cannot start QTcreator
@
under /opt/Qt/Tools/QtCreator/bin
./qtcreator
Error: could not initialize GLX
Aborted (core dumped)
[/quote]
Sounds like broken opengl drivers.
Have you made any changes in the system that may cause to break GLX?
Do you run it in virtual machine?

[quote author="houmingc" date="1420514021"]
when i sudo su
under /opt/Qt/Tools/QtCreator/bin
sudo ./qtcreator
No protocol specified
QXcbConnection: Could not connect to display :0
Aborted (core dumped)
[/quote]
Superuser does not have access to XWindow of a regular user unless you enable it using "xhost +" command.

[andreyc]

Another option.
Is it possible that you were logged into remote machine with X11 forwarding disabled?