QQXcbConnection: Could not connect to display

[Shidharth]

I have created C++ console application to convert HTML to PDF using Qt WebKit. it is working fine when running the application using terminal. I have started the console application in web application using C#.

When I deploy it using nginx, it throws below error, QQXcbConnection: Could not connect to display .

Qt version: 5.5
OS: Ubuntu 16.04

I have deploying the application in localhost.

Can anyone help me to resolve this?

[jsulm]

@Shidharth Can you show the pro file?

[Shidharth]

I have set below ENVIRONMENT variable and it is working fine.
DISPLAY=:0.0;
XAUTHORITY='/home/username/.Xauthority';