When collaborating with other team members, all team members should be using the same version of the Unity Editor. This is because when a project from a previous version of Unity is opened in a more recent version, project files are upgraded to be compatible with the new version. These files may not be compatible with earlier versions of Unity in use by other team members.
For this reason, it’s important to consider when to upgrade Unity so that all members of the team are able to upgrade at the same time.
Unity Collaborate checks for changes in Unity versions, and issues the following warning to team members who are about to publish changes with a different version of Unity:
If one member of the team upgrades, all of other team members must also upgrade to the same version of Unity.
See the Unity Upgrade Guides to learn more about the impacts of upgrading a Unity project.