When I open Software Update, I have:

An update is available for your Mac

  • macOS Catalina 10.15.4 Update

When I click on "Update Now", I have a window with:

To update, you must restart your Mac.

If I click restart, I effectively restart but when I try to update it asks to restart again.

I have a MacBook Pro (Retina, 13-inch, Early 2015) and 12.29GB available.

  • You need about 20gb of free space to install Catalina so I'm guessing the updates require almost the same amount. I think it's doing a bunch of disk swapping during the restarts. try to get more free space and see if that helps.
    – fsb
    Mar 25 '20 at 20:58
  • @fsb You are right. I free up some space and the update succeed. I wonder why Software Update is not checking the available disk space and alerting the user. Please add an answer, and I will accept it and upvote it. Mar 25 '20 at 22:00
  • Glad to see you got it working! Thanks for the feedback and I’ll add it as an answer.
    – fsb
    Mar 26 '20 at 3:58

You need at least 20GB to install Catalina (macOS 10.15). Updating this OS probably requires the same amount of space.

I’m guessing that your constant restarts are due to the installing not having enough free space so it’s swapping info from the disk to memory.

Try to free up as much disk space as you can, the more the better. Once you get to 20GB, you should be ok. This answer is based on my personal experience with updating many OS versions over the years.

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .