Qtcreator cannot be debugged in Linux

I am using the Ubuntu Linux operating system. The phenomenon is that when QT creator starts debugging, it prompts "you can't do that without a process to debug ". This problem has plagued me for a long time. Most of the answers on the Internet are to set the program to debug mode, but my program is debug by default. Today I found a similar solution on the English website.
 

In/etc/lD. so. conf. create a new file in the D folder, such as QT. so. conf, add a line of statement, "/opt/QT /.. /lib ", note that you should replace it with the installation path of QT lib on your machine. Do not enclose it in quotation marks and save and exit. Run "sudo ldconfig" on the terminal ". Now let's see if your qtcreator can be debugged.