How to combine PDF/X format files into one PDF/X

[Grisha5E8D]

I want to combine my pdf files into one,because printing company wants all in one pdf and format -> PDF/X. But when I'm trying to combine all pdf/x files into one with adobe acrobat,it's showing this -> "one or more of your files are pdf/x compliance. to retain this compliant choose PDF portfolio option."

[Test Screen Name]

They aren't made to be combined, because each one is complete and has document-wide settings like Output Intent and others. To combine files made with different Output Intent would be sure to make a bad result, with bad printing quality, and ruin the whole reason for making PDF/X in the first place. So combining is locked out. If you are sure the files are identically made, you could remove PDF/X status in preflight, combine them, then put PDF/X status back on with the original settings. Be sure you understand PDF/X properly before attempting this, or you could ruin a very expensive print job.

[Grisha5E8D]

But they want all in one PDF/X . . . Can I export high printing quality ? and then combine them with pdf/x

Or can I combine all files into one pdf  portfolio option

[Test Screen Name]

Export from what? Not Acrobat...

[Grisha5E8D]

No,from Adobe Illustrator, then combine all pdf files into one from Adobe Acrobat and make it PDF/X?

[Test Screen Name]

 By the way, a printer who asks for PDF/X is certain to reject a portfolio, because the portfolio cannot itself be PDF/X.