PDFBox creates corrupt PDF files

In some cases, when a PDF document is splitted page by page and then merged again into one or several PDF files, Acrobat Reader produces an "Error 14 - A problem occured when reading the document" message.

The message is not shown when opening the document, but when scrolling downwards from the first page to the second. This happens on different machines. The original PDF files do not cause the error to be displayed.

Acrobat reader continues working, but doesn't display some pages (see screenshot). In the specific case, page 1 and 4 are displayed, page 2 and 3 remain undisplayed.

Additionally, I was unable to find out what's the case when "Error 14" is displayed. When browsing for the problem you'll find people saying that this happens when the file isn't standard-conform, but I found no reliable source for this explanation.

At the moment I cannot provide a file to reproduce as those files are confidential, but I'll try to provide an anonymized version.