In v28, when exporting PDF/X-4 via an Action or script, inserting a "Convert to Working CMYK" step into the workflow allowed consistent production of PDF/X-4 compliant files with no preflight errors.

In v30, following the exact same workflow with identical files and the same preset now produces non-compliant PDFs. Acrobat preflight reports two distinct errors that did not occur in v28.

Preflight Error #1 — Placed image ICC profile conflict:
"CMYK source profile is the same as the PDF/X output intent destination profile (201 occurrences, 2 pages)"

Cause: Placed PSD files have Japan Color 2001 Coated embedded as an ICC profile. Since the output intent is also Japan Color 2001 Coated, v30 appears to write both into the PDF in a way that triggers a conflict. This did not occur in v28 with identical source files.

Preflight Error #2 — Transparency blend color space conflict:
"Transparency blend color space is the same as the output intent destination profile (13,681 occurrences, 2 pages)"

Cause: v30 appears to embed the document's transparency blend space (Japan Color 2001 Coated, derived from the working CMYK setting) in a way that conflicts with the output intent. This also did not occur in v28.

PDF Preset Settings (X4_Johnset):
- Standard: PDF/X-4:2010
- Compatibility: Acrobat 7 (PDF 1.6)
- Color Conversion: No Conversion
- Output Intent Profile: Working CMYK — Japan Color 2001 Coated
- Profile Inclusion Policy: Include All RGB & Tagged Source CMYK Profiles

Both errors are absent when exporting the same file with the same preset from v28.7.10. This appears to be a regression introduced in v30.

Is there a known workaround? Is this a confirmed bug?

Environment:
- Hardware: MacBook Pro 16-inch (November 2023), Apple M3 Pro, 36GB RAM
- OS: macOS Sequoia 15.7.4
- Illustrator version with issue: v30.2.1 (2026)
- Illustrator version without issue: v28.7.10 (2024)

Thank you for the continued development of Adobe Illustrator. I am a professional graphic designer working in prepress and print production, and I greatly appreciate the dedication your team puts into this product. I would like to report what appears to be a regression introduced in Illustrator v30.

— Reported by I'm John