Unable to update using tlmgr

[R (Chandra) Chandrasekhar]

Dear Folks,

I have just installed TeXlive 2020 on Linux without any errors.

I tried

tlmgr --repository http://www.ctan.org/tex-archive/systems/texlive/tlnet 
update --self --all

and have been repeatedly getting the following error:

---
/home/chandra/extra/texlive/2020/bin/x86_64-linux/tlmgr: signature 
verification error of /tmp/oLo9xQRQc4/i6uD0HIwuL from 
http://www.ctan.org/tex-archive/systems/texlive/tlnet/tlpkg/texlive.tlpdb: 
cryptographic signature verification of
   /tmp/oLo9xQRQc4/yb95STBX3Q
against
 
http://www.ctan.org/tex-archive/systems/texlive/tlnet/tlpkg/texlive.tlpdb.sha512.asc
failed. Output was:
gpg: Signature made Thu 14 May 2020 20:04:16 IST
gpg:                using RSA key 4CE1877E19438C70
gpg: BAD signature from "TeX Live Distribution <tex-live at tug.org>" 
[ultimate]

Please try from a different mirror and/or wait a few minutes
and try again; usually this is because of transient updates.
If problems persist, feel free to report to texlive at tug.org.
---

I am reporting as advised as the problem has persisted.

I am also unable to compile files on TeXLive 2020 that could be compiled 
without error on TeXLive 2019, and the errors are puzzling.

Before I post a question on TeX Stackexchange, I want to rule out a 
flaky TeXLive 2020 installation.

Thank you.

Chandra