That’s why macOS 10.14 support may be discontinued at the end of this year. However, macOS 12 Monterey will be released later this year. Therefore, support is currently only available on macOS 10.14, 10.15, and 11. This means that when a new macOS version is released, OneDrive will support this new update and the previous two updates. Microsoft also states that it will only support the latest three versions of macOS going forward. This change affects both personal and business accounts. In addition, the application cannot be installed on a version of macOS that does not support the OneDrive sync client. Users may also miss certain security updates. Although the apps will continue to work for now, the issues that occur in these versions will not be fixed. After the specified date, users who have already installed OneDrive will no longer receive any updates. Support for the OneDrive sync client in these macOS versions is set to end on September 10.

So much so that these versions of macOS are no longer supported by Apple. The OneDrive sync client will no longer support macOS 10.12 Sierra and 10.13 High Sierra. Microsoft has ended support for the OneDrive sync client in older versions of macOS. OneDrive sync client support for macOS 10.13 is being discontinued.