All project references have yellow triangles every time solution is loaded

Question

All my project (from the same solution) references are marked with a yellow triangle. The projects are all set to the same .NET version (4.5.1). The error log says:

Answer 1

I had the same thing happen but didn't suspect the 24 warnings I was getting was related to this error: Error 1 Unable to locate the .Net framework aspnet_merge.exe tool on path '~\Photo Archive\Main\etc\tools'. You need to set the msbuild property 'AspnetMergeToolPath' to the folder containing this tool. ODOT.PhotoArchive.Web

Trying to set the MS build property led to a lot of research just to find out WHICH property to set. So, Agent Ransack to the rescue -- searched my drive for the most recent version of the tool and copied it to the directory Visual Studio was complaining about.

Rebuilt the project with the idea of clearing the error but then the 24 warnings also disappeared.

FYI -- this is an MVC project which will replace a classic asp project. This might be peculiar to MVC projects.

At any rate, there was a lot of chasing snipes before this was finally tried. So, where this is happening, try handling any errors no matter how remote the possibility is they're related to the issue.