ASP.NET Visual Studio Error Source XXX could not be opened ('Unspecified error ')

 

 

1 Error    1    Source file 'D:\Projects\LabServicePlatform\dev\LabServicePlatform\LabServicePlatform\Models\SettingQueryParams.cs' could not be opened ('Unspecified error ')    LabServicePlatform
2 Error    2    Source file 'D:\Projects\LabServicePlatform\dev\LabServicePlatform\LabServicePlatform\Models\PGMQueryParams.cs' could not be opened ('Unspecified error ')    LabServicePlatform
3 Error    3    Source file 'D:\Projects\LabServicePlatform\dev\LabServicePlatform\LabServicePlatform\Utility\Util.cs' could not be opened ('Unspecified error ')    LabServicePlatform
4 Error    4    Source file 'D:\Projects\LabServicePlatform\dev\LabServicePlatform\LabServicePlatform\Models\ModelExtensions.cs' could not be opened ('Unspecified error ')    LabServicePlatform