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sidebar_current: "installation-backwards-compatibility"
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# Backwards Compatibility

## For 1.0.x

Vagrant 1.1+ provides full backwards compatibility for valid Vagrant 1.0.x
Vagrantfiles which don't use plugins. After installing Vagrant 1.1, your 1.0.x environments should
continue working without modifications, and existing running machines will
continue to be managed properly.

If you use any Vagrant 1.0.x plugins, you must remove references to these from
your Vagrantfile prior to upgrading. Vagrant 1.1+ introduces a new plugin
format that will protect against this sort of incompatibility from ever
happening again.

If your Vagrantfile doesn't just work with 1.1 and doesn't use any plugins,
please [report a bug](https://github.com/mitchellh/vagrant/issues).

## For 1.x

Backwards compatibility between 1.x is not promised, and Vagrantfile
syntax stability isn't promised until 2.0 final. Any backwards incompatibilities
within 1.x will be clearly documented.

This is similar to how Vagrant 0.x was handled. In practice, Vagrant 0.x
only introduced a handful of backwards incompatibilities during the entire
development cycle, but the possibility of backwards incompatibilities
is made clear so people aren't surprised.

Vagrant 2.0 final will have a stable Vagrantfile format that will
remain backwards compatible, just as 1.0 is considered stable.