【完整错误】16:43:40: The process failed to start. Either the invoked program "/home/xiaojin/QT_code/QT_TCP_CLIENT/build/Desktop_Qt_5_15_0_GCC_64bit-Debug/QT_TCP_CLIENT" is missing, or you may have insufficient permissions to invoke the program.
解决方法：删除build文件夹下除了.h文件以外的文件
红框内的全部删除，再次打开项目就能运行了。