That’s good news for SharePoint developers, the SystemUpdate method is finally available in Client Side Object Model.
Indeed, Microsoft has recently released an update for nugget packages and the method is part of the new stuff.
It’s an important method because it allows you to update a list item without changing modification date, author, publishing and versioning information.
Moreover, we’re numerous SharePoint developers migrating a lot of full trust solutions to SharePoint Add-ins, some of which were using this method and in some cases we have only an app-only context. Usage of this method instead of the regular update method will avoid having documents last updated by “SharePoint App”.
However, this version is only available when coding against SharePoint Online and not for SharePoint 2013/2016.