[Koha] ILL backends - Libris YAML error

[Fairlamb, Christina]

Hello all,

I'm having an issue with the Libris ILL install and wondered if anyone
could help.

I get a 500 error going to the ILL requests -> new request (Libris). This
is the error I see in plack-error.log after the first attempt after an
update or reboot:

Can't locate YAML/Syck.pm in @INC (you may need to install the YAML::Syck
module) (@INC contains: /usr/share/koha/lib /usr/share/koha/installer
/usr/share/koha/lib/installer /etc/perl
/usr/local/lib/x86_64-linux-gnu/perl/5.32.1 /usr/local/share/perl/5.32.1
/usr/lib/x86_64-linux-gnu/perl5/5.32 /usr/share/perl5
/usr/lib/x86_64-linux-gnu/perl-base /usr/lib/x86_64-linux-gnu/perl/5.32
/usr/share/perl/5.32 /usr/local/lib/site_perl) at
/usr/share/koha/lib/Koha/Illbackends/Libris/Base.pm line 23.
BEGIN failed--compilation aborted at
/usr/share/koha/lib/Koha/Illbackends/Libris/Base.pm line 23.
Compilation failed in require at /usr/share/koha/lib/Koha/Illrequest.pm
line 320.

And these two lines appear in every further attempt to get on the page:

Attempt to reload Koha/Illbackends/Libris/Base.pm aborted.
Compilation failed in require at /usr/share/koha/lib/Koha/Illrequest.pm
line 320.

I added Freeform first, and that works fine. I followed the basic
instructions on the Koha ILL backends page and the additional instructions
for Libris on the github page for configuration.

Kind Regards

Christina