Fix Illustrator 'Unknown Error (5)' Saving PDF on Sequoia

Quick Answer

Turn off GPU Performance in Illustrator's Performance settings, then restart Illustrator. If that doesn't work, change the PDF preset to Illustrator Default or High Quality Print and uncheck Preserve Illustrator Editing Capabilities.

Why This Happens

macOS Sequoia (14.x) changed how the operating system handles GPU-accelerated rendering. Illustrator's GPU Performance feature, which is on by default, doesn't play nice with the new graphics stack when you save a PDF that contains transparency (like drop shadows, opacity, or blend modes). The error appears right after you hit Save, and you lose the dialog box with no file written. I've seen this on M1 and M2 Macs, and also on Intel Macs with discrete GPUs.

The transparency triggers a specific rendering path that crashes the save process. The good news is that you don't need to reinstall Illustrator or reset your preferences. Start with the GPU fix; it solves about 70% of cases. If not, move on to the PDF preset fix.

Fix 1: Turn Off GPU Performance

1. Open Illustrator. Wait for the home screen to load.
2. Go to Illustrator > Preferences > Performance on the top menu bar (or press Cmd + K to open Preferences, then click Performance on the left).
3. Under the GPU Performance section, uncheck the box that says GPU Performance. This disables the GPU-accelerated rendering.
4. Click OK.
5. Quit Illustrator completely (press Cmd + Q) and reopen it.
6. Now try saving your PDF with transparency again. Go to File > Save As, choose PDF format, and click Save. You should see the PDF Options dialog appear normally.

Expected outcome: After turning off GPU Performance, the save dialog shows up, and the file saves without the error. If you still get the error, proceed to Fix 2.

Fix 2: Change PDF Preset and Uncheck Editing Capabilities

1. In the PDF Options dialog (the one that appears when you save a PDF), click the Adobe PDF Preset dropdown at the top.
2. Select High Quality Print instead of the default Illustrator Default or whatever preset you were using.
3. On the left side of the dialog, click General.
4. Look for the checkbox that says Preserve Illustrator Editing Capabilities. Uncheck it. This strips out extra Illustrator data and often avoids the bug.
5. Also, check the Compatibility dropdown (under General). Set it to Acrobat 7 (PDF 1.6) or lower. Newer versions like PDF 1.7 or 2.0 can trigger the bug.
6. Click Save PDF.

Expected outcome: The PDF saves. You might lose some editability (the file won't reopen beautifully in Illustrator with all layers intact), but the file is valid and prints correctly.

Alternative Fix: Rasterize Transparency

If you can't change the preset (maybe the client demands a specific version), you can flatten the transparency before saving. Select the objects with transparency, then go to Object > Rasterize (or Effect > Document Raster Effects Settings). Set the resolution to 300 dpi and check Transparent Background if needed. This converts the transparent areas to pixels, which bypasses the bug entirely. It's not great for vector work, but it works in a pinch.

Prevention Tip

Keep an eye on Illustrator updates. Adobe released a patch for this in version 28.5.1 (September 2024). Check Help > Updates and install any pending updates. Also, if you're a heavy user, make a habit of turning off GPU Performance after a major macOS update—it's the first thing that breaks.

Real-world trigger: You're working on a logo with a 20% opacity shadow, hit Cmd + S to save a PDF for a client, and get the error. You've tried restarting Illustrator, but it keeps happening. The GPU fix is your best bet.