(c) Encrypted PDF document: If some security settings such as password or certificate are added on a PDF file, then the PDF document becomes encrypted, which restrict to make any changes on PDF file.

In this setting, the author or distributor of the PDF-file does not allow you to add comments to it. (b) Secured or protected document: The security settings of the PDF document clearly restrict you to add the comment on PDF document. (a) A Scanned PDF document containing no real text: When Adobe acrobat highlight tool is not working, then it is possible that your PDF file is likely a scanned file that containing no any real text. Some of the most common cases are discussed below: There are many situations where users are unable to use highlight text in PDF or add comments on it. Does anyone know how to enable highlight option in Adobe Reader?” Why Users Can’t Highlight PDF in Adobe Reader? It does not give me permissions to highlight text in PDF files.

But, I have found that the Adobe Acrobat highlight tool not working. I want to highlight some important lines in it. “I am reviewing a magazine that is downloaded in PDF file format.

How to remove highlight in pdf