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Home / Blog / Why Can’t I Highlight Text in PDF? | Causes and Solutions

Why Can’t I Highlight Text in PDF? | Causes and Solutions

By Lena | Follow twitter | Updated on April 9, 2024
Can't highlight text in PDF is a common problem many users report. If you also have difficulty highlighting text, don't miss this article. You will know why this problem occurs and the solution.  

Why Can’t I Highlight Text in PDF?

Highlighting text in a PDF document can emphasize key points and improve readability. For study material, highlighting the essential parts can help us be more efficient when reviewing. But now you find that you cannot highlight text in PDF. Why? Here are the possible causes of the problem.

# It is an image-based/scanned PDF.

The most likely reason is that the PDF is not a text-based document. That is, the PDF is a collection of images, and the "text" is part of those images. In this case, you can't even select the text, let alone highlight it.

Solution - Use the OCR tool to convert the PDF and make it editable.

# The PDF is protected from editing.

The author of the PDF may not want the content to be modified by others, so security settings are applied. You can’t highlight text in PDF files with editing disabled.

Solution - Ask the PDF owner for the password or request he/she resend the PDF without security settings applied. You can also use an online service to remove the editing lock.

# The PDF file is corrupted.

The PDF file may be corrupted, so the text cannot be highlighted. File corruption can occur due to an error during the creation or transmission.

Solution - Re-download the PDF or request the author of the PDF to resend a copy.

# The PDF reader error.

Some PDF readers do not support highlighting text. Even if you are sure that the text highlighting feature is available, it may be outdated and, therefore, generate an error that prevents the text from being highlighted.

Solution - Use a PDF editing tool that supports highlighting and ensures it is up-to-date.

For more information about the solution, see the next section.

Solutions to Can’t Highlight Text in PDF

In the previous section, we explained the reason for the problem and its solution. If you are confused about some solutions, you can get more details here.

Fix 1. Try Another PDF Tool

If you are sure that the PDF file is not corrupted, you can check if it is because of a problem with the PDF tool you are using. The easiest way to do this is to open the PDF with another tool and highlight the text.

Click the download button below to get SwifDoo PDF, a popular Adobe Acrobat alternative.

Here is how to use SwifDoo PDF to highlight text:

1. Launch SwifDoo PDF and drag the PDF to its window.

2. Choose Highlight and select a color.

Choose Highlight

3. Now, you can go to the page to highlight text.

Highlight with SwifDoo PDF

Note: SwifDoo PDF offers various annotation tools to help you annotate PDFs. In addition to highlighting, it allows you to draw lines, add shapes, and use a pen tablet to handwrite on the PDF page.

Fix 2. OCR PDF to Make It Editable

If the problem persists after using another PDF reader, the file may be an image-based PDF file. That means you can't edit the text. You can use SwifDoo PDF's OCR (Optical Character Recognition) technology to convert the PDF to an editable one. The detailed steps are as follows.

1. Open the PDF file with SwifDoo PDF > Click Edit from the menu bar > Choose OCR.


2. On the pop-up box, select the language, output, and page range > Click Apply to save the changes.

Adjust OCR Settings

3. Wait a few seconds, and you will see a new editable file. Now, you can select the text and highlight it.

Highlight Text in Scanned PDF

Fix 3. Remove Editing Lock

You cannot highlight text in a PDF that has editing restrictions. If you can't contact the author or distributor, you can use an online service to remove the editing tool. Let me take Online2PDF.com as an example.

1. Open your browser and go to https://online2pdf.com/remove-pdf-editing-lock.

2. Click Select files to upload the PDF.

Upload PDF

3. Rename the file if needed and click Convert to start.


4. Save the PDF to your device.

Fix 4. Fix the PDF If It’s Corrupted

The PDF may be corrupted during the download or transfer process. If all the above do not work, you can try to fix this PDF. Online services can help you repair a corrupted PDF file, including iLovePDF, PDF2Go, and Recovery Toolbox. All you have to do is upload the PDF to the server and it will try to fix it.

1. Go to an online service like iLovePDF: https://www.ilovepdf.com/repair-pdf.

2. Click Select PDF file to upload the PDF.

Repair PDF

3. Click Repair PDF and download the file.


Can't highlight text in PDF is an annoying but solvable problem. The most likely causes are that the PDF is image-based or has editing restrictions. Hopefully, this article can help you find the cause of the problem and successfully fix it.

Can't Highlight Text in PDF FAQs

Q:Why can't I highlight text in PDF on Mac with Preview?

There are two possible reasons: it is a scanned PDF, or has security restrictions. Solution: Use OCR to make the text editable; contact the file producer to request the password or a version that is not subject to these restrictions.

Q:How can I check if a PDF has highlighting restrictions?

You can check the document properties or security settings in the PDF reader. This section will list any restrictions on the document, including whether or not highlighting is allowed.

Q:Is it legal to remove highlighting restrictions from a PDF?

Removing highlighting restrictions without appropriate permissions is generally not recommended, as this may be illegal. It is best to obtain permission from the document owner.

Lena has been in the editing industry for 8 years. She is familiar with a variety of products that can make things easier, such as PDF tools, video recording software, iOS location changer, etc. She enjoys sharing her knowledge with users to help them solve problems in their work and life. In her spare time, she likes to play with her cat.

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