redis.template.yml should be a part of data.yml
I just performed a git pull followed by ./launcher rebuild web_only and it completed successfully.
Have you tried using ./discourse-doctor although it may not help much.
If you can still boot up your old container using ./launcher start web_only then maybe try taking a full backup (as insurance) then try ./launcher stop web_only; ./launcher rebuild data if no errors occur in rebuilding data then try ./launcher rebuild web_only to see if that fixes the problem?
in the meanwhile, I’m moving this topic to Support due to lack of a consistent repro.