visual studio 2017 - Warnings in VS2017 but all fine with VS2015 -

when load .net frameowrk 4.6.2 solution in visual studio 2017, gives me following warning:

severity code description project file line suppression state warning project not referencing ".netframework,version=v4.6.2" framework. add reference ".netframework,version=v4.6.2" in "frameworks" section of project.json, , re-run nuget restore. 

another:

warning ide0006 error encountered while loading project. project features, such full solution analysis failed project , projects depend on it, have been disabled.   bigdata     1   active 

however, loading in visual studio 2015 totally fine same solution files , structures.

why , how can solve it?

btw, read, in latest updates, project.json merged .csproj, why here it's still recommending on project.json

i had show error when building shortly after migrating solution vs2015 2017, , doing git restructuring. turns out, think git culprit.

regardless, manually deleting bin & obj folders in affected projects solved me. (clean alone wasn't cutting it.)