I have a solution that builds fine in VS2015. I just installed VS2017 RTM and after conversion, attempts to build the solution fail immediately with the error:
The problem seems to be with the new lightweight solution loading feature of VS2017.
To fix it, first clean up:
.vs
folderAfterwards, don't re-enable lightweight solution loading for that solution.
You can completely disable lightweight solution loading for all solutions in the options, but if the problem only applies to some solutions then that might be a bit heavy handed.