@kevinguo said in qtcreator and QT apps fail to launch in CentOS with root privilege: Hi: I am using CentOS 8.1. For some reason, I must run my app with root permission. I tried #sudo myapp or #sudo su #myapp Both failed with following output: QStandardPaths: wrong ownership on runtime directory /run/user/1000, 1000 instead of 0 No protocol specified qt.qpa.screen: QXcbConnection: Could not connect to display :1 Could not connect to any X display. Then I tried launching qtcreator, but failed with the same error. Please note that I am able to launch QT apps in Ubuntu 18.04 with root permission in the same way. Ubuntu outputs the following warning but continues to run the app: QStandardPaths: wrong ownership on runtime directory /run/user/1000, 1000 instead of 0 The failing platform is CentOS 8.1. The XWindows is wayland. Now, the workaround is to log in GUI with root user name. But I still prefer logging in as normal user then run app in sudo mode. I appreciate if anyone gives some advice. Kevin I found the solution already. Just run this: xhost +SI:localuser:root Thanks Kevin