https://wccftech.com/windows-10-1809-blocked-more-machines/

It’s been over two months since the initial release of Windows 10 1809 and there is no stopping the issues that continue to push Microsoft to put upgrade blocks in place. The Windows maker has now confirmed a fresh new problem that could result in some users being unable to save Microsoft Office documents.

The problem has been identified on devices that have installed Morphisec Protector or another application that uses the Morphisec SoftwareDevelopment Kit (SDK). Microsoft explains: