I am unable to update my software to 10.15.6. I have gone thru all the steps

For whatever reason my MacBook Air will not update to the latest software 10.15.6. I click on update now and it does a restart and it brings me back to the same screen showing me that there is the 10.15.6 update. I have gone thru this process 6 times and get the same result. I even made sure that there was enough storage space. does anyone have any suggestions?