After updating to macOS Tahoe 26, many Mac users encountered the same problem: text highlighting in PDFs through the Preview app stopped working properly. Instead of the familiar yellow highlighter around text, blue rectangles appear, sometimes highlighting doesn't work at all, and it works on one page but not on another.

This isn't a problem with a specific file. It's a system bug affecting many users — especially when working with documents containing tables: bank statements, invoices, contracts.

Why This Happens

The exact cause hasn't been established by Apple yet, but among the most likely:

— Corrupted or outdated Preview app cache files

— Incompatibility of the new PDF renderer with some file formats

— System glitches after the macOS update

Method 1. Re-save PDF via Print

The simplest method — and it helps in most cases.

1. Open the PDF in Preview.

2. Press Cmd + P.

3. In the lower left corner, click "PDF" → "Save as PDF".

4. Save the file under a new name.

5. Open the new file and check highlighting.

After this, the PDF regenerates, and highlighting usually starts working normally.

Method 2. Export as PDF/A

PDF/A is a standardized archival format. Some users report that the problem disappears after export.

1. Open the PDF in Preview.

2. Go to: File → Export.

3. In the format list, select PDF/A.

4. Save the file and reopen it.

This method doesn't always work, but it's worth trying if the first one didn't help.

Method 3. Clear Cache and Launch in Safe Mode

Corrupted cache files can interfere with proper text highlighting.

Step 1. Clear Preview cache:

1. Open Finder → Go → Go to Folder.

2. Enter ~/Library/Caches/com.apple.Preview and press Enter.

3. Delete the folder contents.

4. Restart Preview and check the PDF.

Step 2. If that doesn't help — launch Mac in safe mode:

1. Shut down your Mac.

2. Intel: turn on and immediately hold Shift. Apple Silicon: hold the power button, select the disk, hold Shift → "Continue in Safe Mode".

3. Check highlighting in safe mode.

4. Restart Mac in normal mode.

Safe mode clears system cache and disables third-party extensions — this helps determine whether the problem is related to macOS or installed software.

If Nothing Helped

Sometimes the cause runs deeper: a conflict between system components or an update error. If none of the methods worked — come in for a free diagnostic at iClub.pro. We'll identify the cause and restore your Mac to normal operation. You can book online or by phone.