The OneDrive engineering team is committed to bringing you the best, most secure, end user experience possible. To support that commitment, the OneDrive Desktop application (sync client) will look to phase out support for Mac OS X Yosemite 10.10 and 10.11. These changes will go into effect February 1st, 2019.
Note: Mac OS X Yosemite 10.10 has been out of mainline support since August 2017.
To ensure a smooth transition we recommend that you upgrade machines to Mac OS X 10.12 or above before February 1st, 2019. We do recommend updating to macOS Mojave 10.14 for the best experience.