For a long time I had problems upgrading Win 10 to ver 20H2. I finally called MS and this was their solution
Please click on the link to start download https://download.microsoft.com/down...b-a3fe-140a5e09c9ff/MediaCreationTool20H2.exe
Open the file after it downloaded.
You need to be an administrator to run this tool.
On the License terms page, if you accept the license terms, select Accept.
On the What do you want to do? page, select Upgrade this PC now, and then select Next.
After I did this it finally updated but did take a few hours because I was so far behind the updates.
Please click on the link to start download https://download.microsoft.com/down...b-a3fe-140a5e09c9ff/MediaCreationTool20H2.exe
Open the file after it downloaded.
You need to be an administrator to run this tool.
On the License terms page, if you accept the license terms, select Accept.
On the What do you want to do? page, select Upgrade this PC now, and then select Next.
After I did this it finally updated but did take a few hours because I was so far behind the updates.