Converting multiple files into a one PDF:Error

I suppose you use some fairly recent version of Ghostscript, and the PDF in question uses a CID font which is not embedded.

Therefore the interpreter looks for a substitution font and does not find a suitable one.

See the Ghostscript documentation (file "use.htm") for handling CID fonts. Among other items, it states:

Please note that when a PDF font resource specifies

/Registry (Adobe) /Ordering (Identity)

there is no way to determine the language properly. If the CID font file is not embedded, the Adobe-Identity record depends on the document and a correct record isn't possible when a document refers to multiple Far East languages. In the latter case add individual records for specific CID font names used in the document.

Probably aou need to edit the file cidfmap by hand to define a suitable substitution font (as you didn't tell what system you are using, I cannot tell the

correct path where the said file will reside).

Helge

If the files do not give this error separately, there is an issue with the PostScript wrapper used to combine the files. Probably. Hard to say as you don't share it!