Merge pdf file using libre office draw "could not load file"

was trying merge 2 pdf files… used “insert file” then a pop up appeared “could not load file”

used libre office draw

Same here. It looks you cannot insert pdf files in writer or impress either - see here .
However, you can merge them in two ways:

  1. The obvious way is to open the pdfs separately in different windows. Then manually copy paste the slides/pages from one to the other

  2. Otherwise, you can convert the pdfs into odg format using the convert-to command line parameter first and then inserting the odg files into your document. (Note that whenever you are opening pdf files, it is converted to odg format in draw. And odg is an "insert"able format in draw)

Note: I’m a noob, the experts may be able to give better answers