PDF inclusion: invalid ProcSet array type <dictionary> about pdfjam

[DavidFirth]

It looks like pdflatex (or else pdfpages or something else!) does not like those particular PDF files, for some reason. Have you tried already using xelatex or lualatex, instead of pdflatex for these files? See use of the --latex argument, by looking at output from pdfjam --help. If that solves your problem, please do report back here. It's my only idea, sorry.

[rvernica]

I'm not sure what the problem was, but I think it was related to the document having multiple pages. I went back to Xsane and split the scanned input into two PDFs of one page each. pdfjam worked fine afterwards. Maybe Xsane does not properly encode multiple pages. Or pdflatex does not like that way of encoding multiple pages.

[2ndK16]

I've encountered the same issue, tried to merge a multipage PDF generated by xsane with other PDFs, got the same error message. Adding --latex /usr/bin/lualatex worked fine for me.