VS2013 doesn't fully support explicitly defaulted functions. See https://msdn.microsoft.com/en-us/library/dn457344.aspx#Anchor_1.

Commit b063472 therefore results in several errors beginning with:

error C2610: 'web::details::uri_components::uri_components(web::details::uri_components &&)' :
is not a special member function which can be defaulted

at ...\cpprestsdk\Release\include\cpprest\base_uri.h(35)

It's frustrating but if we want to keep VS2013 support, the hand-written move constructors and assignment operators need to be restored, at least conditionally. (If it's even worth making this conditional, then according to boostorg/config#205, which will add BOOST_NO_CXX11_DEFAULTED_MOVES to Boost.Config, a suitable condition might be _MSC_FULL_VER < 190023026.)