Microsoft Teams is governed by the Modern Lifecycle Policy, the Teams desktop client needs to be under a supported OS version. This is to ensure that users have the latest updates, capabilities, performance enhancements, security features, and service compatibility.

On new Teams, users on OS versions that are not supported will receive in-app notifications to encourage them to update their device to a supported OS version. A version that is too far out of date will become incompatible with the service and the Desktop client will be blocked until the OS is updated.

Windows OSes support dates and lifecycle policy are documented in Product and Service lifecycle page. For example, OSes such as Windows LTSC and OSes under Long Term Serving Channel (LTSC), are not supported as they follow the Fixed lifecycle policy.

MacOS typically receives support for three years following its release, with the end of support coinciding with the launch of the third subsequent major macOS version. For example, once macOS 15 is released, macOS 12 will no longer be supported.