This pdf:
https://commons.wikimedia.org/wiki/File:Onze_Ministers_-_1901.pdf
Doesn't get thumbnails
This pdf:
https://commons.wikimedia.org/wiki/File:Onze_Ministers_-_1901.pdf
Doesn't get thumbnails
qpdf --check Onze_Ministers_-_1901.pdf checking Onze_Ministers_-_1901.pdf PDF Version: 1.7 File is not encrypted File is not linearized No syntax or stream encoding errors found; the file may still contain errors that qpdf cannot detect
My local version of ghostscript does not report any errors processing the PDF, so it's either been fixed by gs 9.52 or the error is somewhere else.
I double-checked this file, and Ghostscript 9.26 does report an error that gs 9.52 does not. It's a non-fatal error though, and it still generates a thumbnail, except for T236240. Now that's been fixed, and thumbnail generation works for the file.