Already referred below old posts, but its solution of installing websocket
s didn't work in my Ubuntu 21.10.
This could be probably due to my Qt is 6.2, while the available library is from Qt5, viz. libqt5websockets5-dev
.
How to install websocket module properly for the Qt6, to fix below error?
Project ERROR: Unknown module(s) in QT: websockets
When installing Qt via Qt Maintenance Tool, just go to Additional Libraries and check QtWebSockets. It is available in Qt 6.2.x versions.