Rails reports this is a "Feature request" that they do not plan to implement, but will welcome pull requests. We may need a way to convert from an MD5 based cache to a SHA256 or to convince rails that it is acceptable to have to rebuild the cache from scratch during an upgrade (if that is at all possible) - See https://github.com/rails/rails/issues/31203

Opened a PR in Rails github project: https://github.com/rails/rails/pull/31289

PR has been merged: https://github.com/rails/rails/commit/659c516bef2781cc66865fc78ed5dce682566d26

For testing with Rails < 5.2, also this patch will be needed https://github.com/rails/rails/pull/31490, as the original change included `...` in the digest.