I believe that the import of “PDF” files is a recent feature of QCAD.
I have been using qcad for less than a year and I don’t have a great experience.
I can’t import pdf files. Both by invoking CTRL+Shift+I and from File Menu → Import I am asked to choose the file (and I already agree that the pdf files are not included among those considered importable); However, if I choose a vector pdf file (for example a pdf file generated by a QCAD drawing which is therefore vector), an import error is generated
Qcad Professional
Version: 3.27.6.0 (3.27.6)
Internet: Qcad.org
Compilation date: May 16 2022
Revision: f76bbd6
Qt version: 5.13.2
Architecture: x86_64
Compiler: MSVC ++ 14.0 (2015)
OS Win10