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Hydra since version 1.2 supports backwards compatible upgrades by default through the use of the version_base parameter to @hydra.main() and hydra.initialize().

There are three classes of values that the version_base parameter supports, given new and existing users greater control of the default behaviors to use.

  1. If the version_base parameter is not specified, Hydra 1.x will use defaults compatible with version 1.1. Also in this case, a warning is issued to indicate an explicit version_base is preferred.

  2. If the version_base parameter is None, then the defaults are chosen for the current minor Hydra version. For example for Hydra 1.2, then would imply config_path=None and hydra.job.chdir=False.

  3. If the version_base parameter is an explicit version string like "1.1", then the defaults appropriate to that version are used.