[
{ type: upgrade
  maximum_version: 2.0
  message: <<EOM
Migration from radicale 1.x to 2.x requires that you export the storage
with radicale 1.1.x before it can be used.

Migration instructions: https://web.archive.org/web/20190314225402/https://radicale.org/1to2/
EOM
}
]