Can’t Highlight PDFs in macOS Tahoe 26? Here’s The Real Fix

After updating to macOS Tahoe 26, a lot of Mac users started noticing something strange in Preview. Trying to highlight text in a PDF; something I, like many people, do all the time; no longer worked as expected. Instead of a normal highlight, users would see odd blue boxes around the text. Sometimes nothing happens. Sometimes it works on one page but not another. At first, many assumed it was just a bad file. It wasn’t.

After testing multiple PDFs and reviewing user reports, it became clear this is a widespread issue. Many users are seeing the same behavior — especially in documents with tables like bank statements — and the results are inconsistent and unpredictable. In this article, I explain what you can do to fix this issue.

1. Print the PDF and Save as a New PDF

This is the most commonly suggested workaround when you can’t highlight PDFs in macOS Tahoe 26. I tried printing the file and saving it as a new PDF, and in some cases, it worked. Highlighting started behaving normally again. However, it doesn’t always fix the issue, and repeating this for every document quickly becomes tedious. Here are the steps:

1. Open the PDF in Preview
2. Go to the top menu and click File > Print (or press Command P)
3. In the print window, look for the PDF button (bottom-left corner)
4. Click it, then select "Save as PDF"
5. Save the new file to your desired location
6. Open the newly saved PDF in Preview and try highlighting again to see if highlighting works now.

2. Export the File as PDF/A

Another solution is exporting the document as a PDF/A file. Many users saw some improvement with certain PDFs, but just like the first fix, it’s inconsistent and doesn’t work across all files.

Here’s how to do it:

1. Open the PDF in Preview
2. Go to the top menu and click File > Export
3. In the export window, look for the Format or Quartz Filter option and select PDF/A (sometimes listed as a Quartz filter like Create PDF/A)
4. Choose where to save the file
5. Click Save
6. Open the new PDF and try highlighting again

3. Recreate Caches / Use Safe Mode

This is a more advanced workaround that aims to fix possible system-level issues affecting Preview. Some users reported that missing or corrupted cache files can interfere with features like text selection and highlighting. There are two options:

Option A: Recreate the Caches Folder

1. Open Finder
2. In the top menu, click Go > Go to Folder…
3. Type ~/Library/ and press Enter
4. Look for a folder named Caches
5. If it’s missing: create a new folder and name it exactly Caches
6. If it’s an alias (has a small arrow icon): delete it and create a real folder named Caches
7. Close Finder and restart your Mac

Option B: Boot into Safe Mode (to rebuild caches)

1. Shut down your Mac
2. Press and hold the Power button until you see "Loading startup options"
3. Select your disk
4. Hold the Shift key, then click Continue in Safe Mode
5. Log in and open a PDF in Preview to test highlighting
6. Restart your Mac normally — this will exit Safe Mode
7. Safe Mode automatically clears and rebuilds certain system caches, which can sometimes resolve unusual behavior like this.

See also: How to Fix Drag and Drop Not Working in macOS Tahoe