"File too large to save"

[macdobr]

I am trying to combine a number of smaller PDFs into a single document of 218 pages. The combined size of the documents is under 2.5 GB. I do not wish to save it as an Optimized or Reduced Size PDF. The message I get is "The document could not be saved. The file is too big for the current operation."  These parameters seem well within the maximum size of document that can be saved.

I am using Adobe Acrobat Pro 2020 v. 2020.001.300.3018 (or Acrobat DC v. 21.0 , I cannot tell the difference) on a Mac,  Big Sur 11.2.3.

[ls_rbls]

Is this happening when you use the "Combine Files" tool?

[macdobr]

It happened with the "Combine Files" tool, and then I tried just placing the pages using the "Organize Pages" tool. This is an annual yearbook of approximately 150 pages that I produce using InDesign and then I upload press-ready PDFs to the commercial printer. I wanted to collate the various PDFs that I upload back into a single document to archive at the organization that produces the yearbook. Interestingly enough, I was unable to do this for years 2014 and 2015, but was then able to use the Organize Pages function to produce a single PDF document of 1.86 GB for year 2016. (The separate 2016 PDF files that were uploaded to the printer totalled about 1.873 GB).

So I am mystified why I was not able to combine years 2014 and 2015, but was able to combine year 2016.

I am going to try 2017 to see what happens.