[Koha] Problem upgrading to 21.05: perlapi-5-24.1 is not available

[King, Fred]

Esteemed Colleagues,

I'm trying to upgrade my Koha instance from 20.11.01.000 to 21.05, or 21.11 if I can't do oldstable. I'm running it on Ubuntu 20.04LTS.

Short description: the upgrade appears to need perlapi-5-24.1, but it's not available.

Long description, my input is in (parentheses); system response is indented in courier:
(while upgrading)
E: Repository 'http://debian.koha-community.org/koha stable InRelease' changed its 'Codename' value from '20.11' to '21.11'
N: This must be accepted explicitly before updates for this repository can be applied. See apt-secure(8) manpage for details.
(so I typed: echo 'deb http://debian.koha-community.org/koha 21.05 main' | sudo tee /etc/apt/sources.list.d/koha.list)
(I also tried the above with 21.11)
(apt-get install koha-common)
koha-common: Depends: libyaml-libyaml-perl but it is not going to be installed
E: Unable to correct problems, you have held broken packages.
(apt-get install libyaml-libyaml-perl)
The following packages have unmet dependencies:
  libyaml-libyaml-perl : Depends: perlapi-5.24.1 but it is not installable
E: Unable to correct problems, you have held broken packages.
(apt-get install perlapi-5.24.1)
Package perlapi-5-24.1 is not available, but it is referenced to by another package.
This may mean that the package is missing, has been obsoleted, or is only available from another source
E: Package 'perlapi-5.24.1 has no installation candidate
(locate perlapi)
/usr/share/perl/5.26.1/pod/perlapi.pod (and a few others)

I've searched the Wiki, Google, and elsewhere, but I haven't found an answer. However, I've been working mostly in my basement and have a bad case of Basement Brain. Could someone point me towards a solution?

Thanks,

Fred King, MSLS, AHIP
Medical Librarian, MedStar Washington Hospital Center
fred.king at medstar.net<mailto:fred.king at medstar.net>
202-877-6670
ORCID 0000-0001-5266-0279
MedStar Authors Catalog: http://medstarauthors.org

I don't know much about being a millionaire, but I'll bet I'd be darling at it.
--Dorothy Parker

----------------------------------------------------------------------
MedStar Health is a not-for-profit, integrated healthcare delivery system, the largest in Maryland and the Washington, D.C., region. Nationally recognized for clinical quality in heart, orthopedics, cancer and GI.

IMPORTANT: This e-mail (including any attachments) may contain information that is private, confidential, or protected by attorney-client or other privilege. If you received this e-mail in error, please delete it from your system without copying it and notify sender by reply e-mail, so that our records can be corrected... Thank you.

Help conserve valuable resources - only print this email if necessary.