I've noticed that my Windows 10 is no longer updating itself. When I run the Settings app and issue an update command, this message appears.
There were some problems installing updates, but we'll try again later. If you keep seeing this and want to search the web or contact support for information, this may help: (0x80070006)
Of course, standalone updates install well. I have also been able to run a manual update from PowerShell and get Windows 10 to build 14393.970. Plus, Windows Defender keeps updating itself, so updating in general is possible.
I have tried running Microsoft Windows Update Troubleshooter. (The latest version from Microsoft website.) Nothing happened. I have also tried an equivalent from tenforums.com. Not only did it not fix my problem, it broke Windows Defender too. (System Restore came to rescue.)