Add-on upgrades and versions

You should take the following consideration regarding upgrades of your add-on, as well as Sitefinity CMS upgrades:

• You must mark deprecated functionality and persist it in the code for at least one version.
• You must announce breaking changes one version prior to introduction.
• You must list release notes and breaking changes in the <releaseNotes> element of the .nuspec file.
• Add-ons should have a dependency to an equal or higher version of the first available Sitefinity CMS release that supports the add-on functionality. This will ensure the widest range of possible customers. 
  For more information, see Manage add-on dependencies.

  EXAMPLE: An add-on depends on functionality in Sitefinity CMS that is available from version 9.2.6000. The latest available version of Sitefinity is 10.2.6000. You should add a dependency in the .nuspec file for versions >= 9.2.6000. This way all clients with Sitefinity CMS version higher than 9.2.6000 will be able to use the latest version of the add-on.

• You must verify add-ons against new major versions of Sitefinity CMS.
  In case of breaking changes, the dependency on Sitefinity CMS must be limited to the last supported version and you must provide a new version of the add-on for the versions, following the breaking changes of Sitefinity CMS.

  EXAMPLE: An add-on has dependency in the .nuspec file for Sitefinity versions >= 9.2.6000. The latest available version of Sitefinity is 10.2.6000 and it introduces a breaking change in the functionality that the add-on depends on. In this case, you should provide a new version of the add-on for the new version of Sitefinity CMS. You should update the old version of the add-on NuGet package to depend on versions >= 9.2.6000 and >10.2.6000.