Is it Update KB4566782 as I had this problem yesterday and got the message:
Some update files are missing or have problems. We'll try to download the update again later. Error code: (0x80073712
I posted this problem yesterday and used the troubleshooter and also sent feedback to Microsoft.
Holly
PS: If you click on the name of the above update where it describes the update it says near the bottom the following but we should have already, if set as mine is, automatically received this Servicing Stack Update. I don't know whether to try this or not.
Microsoft strongly recommends you install the latest servicing stack update (SSU) for your operating system before installing the latest cumulative update (LCU). SSUs improve the reliability of the update process to mitigate potential issues while installing the LCU and applying Microsoft security fixes. For general information about SSUs, see Servicing stack updates and Servicing Stack Updates (SSU): Frequently Asked Questions.