Summary
PDF documents containing mixed page sizes (8.5x11 and 11x17) fail to print correctly after a recent Acrobat/Reader update. Pages sized 11x17 fail with a PostScript interpreter error on the print device; the same 11x17 content prints successfully when extracted into its own single-size PDF. Rolling back Acrobat/Reader to a prior version on the affected server fully resolved the issue with no further errors.
Environment
Product: Adobe Acrobat / Acrobat Reader (please confirm exact product — Pro/Reader/DC — via Help > About)
Affected version: Believed to be 26.001.21771 (planned update dated Aug 1, 2026) — please confirm via Help > About on the affected machine before submitting
Last known-good version: Version installed prior to the Aug 2026 auto-update (please confirm exact build number)
Print target: Large-format industrial printer connected via an EFI Fiery print server (PostScript RIP)
Platform: Windows Server (print server / RDS host)
Steps to Reproduce
Open a PDF containing a mix of 8.5x11 and 11x17 pages in Acrobat/Reader.
Print the document to a PostScript-based printer/RIP with "Choose paper source by PDF page size" enabled (or equivalent mixed-media handling on the print device).
Observe print job failure specifically on 11x17 pages.

Fix Confirmed
Uninstalling the current (post-update) version and rolling back Acrobat/Reader to the prior version on the print server resolved the issue completely — mixed-size jobs now print without error.
This strongly points to a regression introduced in the PostScript generation code path for mixed page-size documents in the recent update.
Additional Regression Observed: Missing Print Dialog Option
The print dialog in the updated version no longer shows the "Choose paper source by PDF page size" option that was present in the prior version. This option is what allows Acrobat to correctly switch trays/page geometry per page for mixed-size documents, so its disappearance is likely directly related to the mixed-media printing failure described above rather than a separate, unrelated issue.
Additional Notes
The issue began immediately following an Acrobat/Reader auto-update; no other changes were made to the printer, Fiery server, or print server configuration.
No official advisory for this specific regression was found on Adobe's Known and Fixed Issues page as of this report.