see on GitHub

Migration : Changes Related to IAdvancedDocumentSessionOperations

Changes in advanced session operations are accessible by session.Advanced.

GetEtagFor

Documents don't have etags any longer but they use change vectors instead the method GetEtagFor. It has been replaced by GetChangeVectorFor.

MarkReadOnly

Marking documents as read-only isn't supported.

ExplicitlyVersion

The method has been removed. Document revisions configuration doesn't use the ExcludeUnlessExplicit option anymore.

Dealing with Non Authoritative Information

DTC support has been dropped.