2018 13’ MBP w tb. Trying to update to Catalina. What happens is it will download, the download will read 8.09 gb out of 8.09 gb. The progress bar is almost to the end. Then it disappears and says checking for updates, returning me to the upgrade now button. It says that the download was null. When I click upgrade it starts the download over again. Shouldn’t it be on my computer if it finished downloading? Install MacOS never opened. This has happened twice now and it is infuriating! What amI doing wrong?!