lots of problems updating tlmgr

[Boylan, Ross]

I think I've finally updated everything, but it didn't go smoothly and so I thought that was worth reporting.
This was on MS-Windows Server 2019 with TeXLive already installed.  I have admin privileges, and the root of the installation is C:\texlive.
I'm just going to give the highlights.  

At a high level:
1. update from the graphical TLShell failed
2. update from downloaded update script seemed to work, but
3. TLShell failed after and messages indicated tlmgr was *not* up to date
4. tlmgr update --self from within "TeXLive command line" worked.

1. TLShell update fails
==================
I wanted to install a new package and launched the graphical TLShell.  After finding and selecting the package I noticed the "Install marked" button remained greyed, but the "Update tlmgr" button was active (and I think  the "TL Manager up to date?" in the top pane also indicated I needed to update).  So I hit the button.

The terminal that opened had messages that backup was not possible on Windows but "continuing anyway".  However,
"failed self update: texlive.infra (71102 -> 71593) texlive.infra.windows (71041 -> 71447) tlperl.windows (69939 -> 71515)".
Followed by "FATAL ERROR" and a report that backup recovery failed too (presumably since there was no backup).

There wasn't much clue about what went wrong, but it did point to update-self.log, which had a bunch of errors like
"tar: Could not create file tlpkg/tlperl/bin/perl.exe: Permission denied"
All the files mentioned seemed likely to be in use by tlshell and the update script itself (e.g., a bunch of dll's), and I thought that might be the cause.  If it is, that would seem to make the offered updates from the GUI destined to fail.

2. downloaded update script seems to work
====================================
The logs suggested running https://mirror.ctan.org/systems/texlive/tlnet/update-tlmgr-latest.exe; I downloaded it, closed TLshell, and ran it.  To run it required fiddling permissions in the file properties dialogue by checking the box that was something like "OK to run even though from the internet".  This seemed to work.

3. but apparently didn't
====================
Launched TLshell and tried again to install the package (blkarray).  But this produced a pop-up "Back end gone. Last Command: install --dry-run blkarray".  The whole shell closes/crashes after I hit OK on the error popup.  Tried again; same result.

Opened "TeXLive command line" and did
tlmgr install --dry-run blkarray
tlmgr.pl: package repository https://mirrors.mit.edu/CTAN/systems/texlive/tlnet (not verified: gpg unavailable)
===============================================================================
tlmgr itself needs to be updated.
Please do this via either
  tlmgr update --self

4. tlmgr update --self works
=======================

So maybe the previous update didn't take?  Ran tlmgr update -self in the same terminal, which seemed to work, and then tlmgr install to get the package.  Which worked.

I may have closed other programs that I thought might be using the "can't delete files" along the way.  In particular, I think I had an older instance of TLShell already running, which I eventually discovered and closed.