Hi Susan, I appreciate the encouragement, however this "problem" goes far deeper than Internet congestion, COVID, etc. Having long been a supporter of Microsoft (I am an IT Infrastructure Support Engineer by career choice), Windows has become less of an operating system and more of an over-bloated sales and marketing engine (Candy Crush anyone?). Sadly, those who suffer are its users and, at the same time, Microsoft continues to push and pump garbage updates, patches and the like. Microsoft's "service" that boasts automagically updating any/all Windows 10 device, whether the user wants it or not, can/should be a seamless process, but clearly it's not ready for primetime. This posting says it all. For clarity, I've attempted this 1909 to 2004 update both online and offline, using the Windows 10 Update Troubleshooter, Update Assistant and a downloaded ISO from the Microsoft "business" Licensing Portal and still, the result is the same - a never-ending (multi-hour) "pause" of sorts at 59%. Nobody deserves such delays (seriously, 9 hours? Upgrading from Windows 95 to 98, with all them floppy disks, didn't take anywhere close to that) and, to boot, no explanation or error detail in which to further troubleshoot what's going on (wrong) with the update. Shame on Microsoft.
Well, now, look at that...while putting together this thoughtful response, I was (once again) attempting to complete the 1909 to 2004 update on the troubled computer and, after 5-10 minutes of hanging at 59%, I now get a Windows dialog box indicating, "The Windows 10 Installation has failed"...and nothing but an OK button. Progress!