a big change? Perhaps. But this version is not a released version. In the past all version begin with 17.3.xxxx.xxx, but now Microsoft has changed it: As part of recent changes to modernize our engineering system, we’re updating the format of the build version numbers for the sync client. The change is rolling out in January 2018 to our Insiders ring and will be reflected in the other rings. Although the version number is changing, there are no other changes to the rings. The first version is 17.005.0107.0004

Here’s my change log

for all new readers:

No, you do not have to do anything, the Next Generation Sync Client (NGSC == OneDrive.exe) will be updated automatically.

Yes, the NGSC is the Sync client for OneDrive (Personal) and OneDrive for Business and all doclibs in Office 365. And this client is also managing the Sharing parts between The Windows Explorer and Office 365.

[Update 01/31/2018]

So Microsoft released the next version. And this is a released version. The Version has the number 17.005.0107.0006

[Update 02/05/2018]

so this version has only some minor fixes and is a Updated build version format to reflect changes to our engineering system.