“Word, Excel, PowerPoint, Outlook and Lync have not been tested on macOS 10.13 High Sierra, and no formal support for this configuration will be provided,” the company explains. The software giant explains that Office for Mac 2011 does not support macOS High Sierra, so upgrading to this version of the operating system basically means that they won’t be able to use the productivity suite anymore. Apple is expected to release the final version of macOS 10.13 High Sierra as soon as the next month, and with the majority of users very likely to upgrade their devices, Microsoft decided to issue a public warning for customers of its Office suite.