Display issue - Xlib: extension "GLX" missing on display ":0"

[radu.szasz]

Hello there!

I have just begun using Qt after quite a break and meanwhile I have changed the OS from Windows to Ubuntu. I am currently using Ubuntu 12.04 LTS.
I tried writing a test Qt GUI App(one that shows the sum of two numbers) and it worked up to a certain point.
When I run the app, the following message occurs,
Xlib: extension "GLX" missing on display ":0".

When I try to click the SumUpButton, instead of displaying the result in the label I want, there is a rectangle displayed in the label I was telling you about.

Please help me solve this problem.

Thank you!
Radu

[sierdzio]

Qt4 or Qt5? Might be that you are missing some dependencies (mesa).

Please show us your code (just the part that matters).