Upgrading API version
It is recommended that when you are ready to upgrade your API version to the current version, you should add in the versioning header to your requests (as described below) and then attempt test requests to ensure your integration will not break upon fully upgrading.
Once testing is complete, you can go into your dashboard settings and make the full upgrade. After that is complete, you should remove the Lob version header from your requests to ensure all your requests use your global version.
When backwards-incompatible changes are made to the API, a new dated version is released. You have the latest version of the API, version 2020-02-11. You can always view your current version in your Dashboard Settings. You will only need to specify a version if you would like to test a newer version of the API without doing a full upgrade. The API will return an error if a version older than your current one is passed in.
A full list of breaking changes: