Cannot highlight text in a PDF.

You need to select the color of your highlight. Adobe changed their color pallet with the most recent update; unfortunalty, I beleive they made the default color transparent. When you click on the highlight market and when you move across the desired area/text to highlight if you see a blue outline it means you need to select a color. Note the O in the sidebar just under the thumb tack. Click on it and select your desired color. Once you have done this, thereafter each time you attempt to highlight the window / box of color options will open up next to where you're highlighting.  Hope this was helpful. 

It's just unclear to me why we now have to use a workaround for something that we've been doing for years. When I'm balancing my checkbook, I highlight each item on the statement as I match it to my checkbook. In the past, I've always been able to just select the amount and highlight it. NOW, it takes more steps plus it will only allow me to do it on the first page of the document. It doesn't make sense to update software and actually add more clicks limit what the user can do. Pretty much the opposite of good UX.

In my case, I had to chance the opacity of the highlight, which was set to 0%.

The solution is to print to pdf from the document you are trying to highlight.  The 'print' action changes the format to recognizable text!  Now you can highlight!

Here's my solution: open PDFs in Microsoft Word - a program where highlighting is simple, and works the way it's supposed to. I tried for an hour to make it work in Acrobat, and couldn't get it to. Adobe, Acrobat is janky and the tool process is opaque and near unusable. Look at Word, learn, and fix.

Encountered the same issue -- unable to highlight text in pdf docs that had no security protections -- had always previously been able to perform this simple function which suddenly became disabled. The suggestions posted here did not work. After some trial and error, the following change seems to have remedied the problem for me and once again enabled the ability to highlight pdf text (hope this helps):

1) Click account - preferences (upper right circle/pie chart next to notifications bell icon);

2) Under Preferences -- Categories -- click "General" 

3) Under General -- Basic Tools -- check the box next to "Make Hand too select text & images"

For some reason the box was unchecked -- once I checked it and clicked okay highlighting was once again enabled

This is a version problem. The solution is to Save As and select the file format: "PDF/X" and you will be in highlighting heaven...

Furthermore, this will turn on highlighting in the right-click context sensative menu, and you can set properties to default to a particular highlight color. To take highlighting off, select "White..."

I'd been having the same problem on Android... But somewhere in the deep, dark recesses of my mind I remembered being able to do ALL kinds of editing including highlighting at some point.

Having had weird, non-sensical Acrobat UX issues in the past, I left cloud and went, via Files, to "On This Device" and tried again.

Lo & Behold, that was the fix! Again, totally odd UI. 

My 2 BIGGEST pet peeves however are,

1. Being unable to rename a file from inside the document! Totally crazy-making.

2. No batch uploading of device pdfs to the cloud UNLESS they are combined, which really isn't batch uploading at all. 

O

I've had this problem recently.   I've always been able to look up a federal solicitation document (as part of my job) online and print to PDF, then highlight the important parts.  Lately, when I've been printing to Adobe PDF, I've been unable to highlight text in the resulting document.  It just highlights an circular area, not at all related to the text.  I've even tried running the OCR to recognize text, but it doesn't work.  It's very frustrating. 

I finally discovered a solutuion.  When I right click and select Print, I see the options of "Adobe PDF" and "Save As PDF".  If I select print to "Adobe PDF", I am faced with the problem described.  But if I select "Save As PDF", I am able to highlight the text in the saved document.  I am not sure if this "Save As PDF" option uses a Kami PDF extension that I have installed on my browser (MS Edge).  Perhaps it does.  But in short, the way to get around the problem is to not use the "Adobe PDF" option.  Given that I am using a paid license for Adobe Acrobat, this is a problem that should be addressed.