Error populating transaction after 10 anaconda retries: failure: <RPM> from anaconda: [Errno 256] No more mirrors to try
Solution 1:
When you generate your repo, prior to generating the ISO, make sure you are in your working root and do NOT specify ./Packages as an argument to createrepo:
createrepo -dpo . ./ -g ...etc...
and NOT
createrepo -dpo . ./Packages -g ...etc...
Source: https://microdevsys.com/wp/errno-256-no-more-mirrors-to-try/