Do not download Qt6 offline installers from third-party torrent sites or file lockers. Malicious actors have embedded malware in counterfeit Qt installers, specifically targeting developers because they have access to production signing keys.
The Qt6 is a standalone package designed for installing the Qt framework without an active internet connection. For Qt 6, the availability and usage of these installers have significantly changed compared to previous versions. Key Availability Restrictions Qt6 Offline Installer
# Windows (CertUtil) certUtil -hashfile qt-unified-windows-x64-6.5.3.exe SHA256 Do not download Qt6 offline installers from third-party
You downloaded a stub (online) installer by mistake. Fix: Check file size. A real offline installer for Qt6 is never under 1 GB. Qt6 Offline Installer