As I stated earlier, this has nothing to do with the file size, it's due to the use of Identity-H encodings in the original PDF file. Please refer to this post for an explanation of the issue and a possible workaround.

Yes splitting the PDFs into smaller PDFs seems to get rid of the issue.

Operative word is "seems".
If you are absolutely certain that every single one of these smaller PDFs is OK, then it means something extremely weird is occuring and I would strongly suggest you open an issue with our Support team.

But I think you'll find that in one of those PDF files, somewhere, there's at least one page that exhibits the same behaviour. In which case, reading the post I referred to in my last post should help you understand and resolve the problemm.

indeed, i also think you need support here and should contact them asap.

are you merging different pdfs to create a large input, or are we talking about a single large pdf that has been output by some programme / sent to you by a client?

i'm with philippe here, split up the pdf at a single page level, run it through your design and check each one for errors to help locate the cause of this issue.

I did these things as well as some detective work.

It appears that some of the PDFs that we are getting from the customer are causing the issue. When said PDFs are removed from the merged file (yes we are merging many to one). the large file runs fine.

Could it be that the font encoding changes on one PDF and then causes this error for every merged PDF after that?

>> Could it be that the font encoding changes on one PDF and then causes this error for every merged PDF after that?

Hard to say, it all depends on which fonts are defined in which PDF, whether one of them overwrites or simply adds to another's encoding...

In any case, you should contact your customer to see if they can change the way they're generating those specific PDF's or failing that, apply the workaround I explain in the other post I referred to in my earlier comment.