Error when publishing Migrated ASP.Net web application with

Question

we have a requirement to migrated the ASP .Net web app from .Net framework 3.5 to 4.6.2. i have migrated the application to frame work 4.6.2 and able to run the application.

problem comes here when publishing the code. i am getting error:

cannot copy the obj/project.dll to release/project.dll

in migrated (frame work 4.6.2) code, however i dont see any error when publishing the old code(frame work 3.5). i have tried many things:

1. delete the Obj folder from the solution
2. ran msbuild.exe command to publish (custom msbuild xml)
3. restarted the IDE(VS2015)

what else should i do?