The free community version of QCAD does not support DWG. You must buy .
Ensure you have the plugin file (usually a .dll , .so , or .dylib depending on your OS) that matches your QCAD version. Locate the Plugins Folder: Windows: C:\Program Files\QCAD\plugins qcad dwg plugin
It is important to note that the QCAD DWG Plugin is . It is a commercial component developed by RibbonSoft to support the continued development of the free QCAD Community Edition. The free community version of QCAD does not support DWG