I encountered this error today as well. A little background, I had no issues exporting a smaller layout or 50+ map series in the traditional "Share Layout" matter. I am now trying to export Poster Size maps (roughly 3x4 feet), and was given the same error as OP. I realized the layout files were for the newest version of ArcPro, which I do not have. I noticed this because I created my out Layout file for Landscape size Poster maps and did not have an issue. However, once I created my own Layout File for the Landscape Poster Maps, I had the same issue. This is to say that the error did not appear to lie with my use of an older version of ArcPro. When using the Share to PDF option, I am now downloading the file to my local drive rather than my remote work desktop. Using the "Tile oversized" option allows for the entirety of these maps to be exported. The process for each map is lengthy, but is a viable workaround for the options proposed above. I hope this helps!
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