A program database file (.pdb) was created using a newer version of mspdbXX.dll than the one the compiler found on your system. This error usually indicates that mspdbsrv.exe or mspdbcore.dll are missing or have different versions than mspdbXX.dll. (The XX placeholder in the mspdbXX.dll file name changes with each product release. For example, in Visual Studio 2005 the file name is mspdb80.dll.)