Referenced Project gets lost at Compile Time

Question

I have a C  solution with two projects  a service  the main project  and a logger  The service uses classes from the logger  I ve added a Reference to the logger project within the service project  At design time  autocomplete works fine  the logger s classes are visible  references that I use are colored appropriately   I Rebuild the solution  and things go wrong  The references are no longer recognized   The name  Logging  does not exist in the current context  and the classes no longer exist in autocomplete  Removing and reattaching the reference gets me back to the base state of having the identifiers visible to autocomplete   I ve rebooted  cleared all caches  made sure this is the only instance of VS 2010 running on my machine   Is there something obvious  obviously  that I m missing

User · Answer

Make sure that both projects have same target framework version here: right click on project -> properties -> application (tab) -> target framework

Also, make sure that the project "logger" (which you want to include in the main project) has the output type "Class Library" in: right click on project -> properties -> application (tab) -> output type

Finally, Rebuild the solution.

User · Answer

Check your build types of each project under project properties - I bet one or the other will be set to build against  NET XX - Client Profile   With inconsistent versions  specifically with one being Client Profile and the other not  then it works at design time but fails at compile time  A real gotcha   There is something funny going on in Visual Studio 2010 for me  which keeps setting projects seemingly randomly to Client Profile  sometimes when I create a project  and sometimes a few days later  Probably some keyboard shortcut I m accidentally hitting

[c#] Referenced Project gets "lost" at Compile Time

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