error MSB4075: The project file must be opened in VS IDE and converted to latest version before it can be build by MSBuild
Anyway - when I first started looking at MSBuils a while ago I was happy to see that csproj and vbproj files are simply MSBuild files now, which, again, boosted my confidence with this approach; I was slightly concerned that BizTalk project files have not been modifed to be MSBuild files but I guess this is understandable given the dependency between BizTalk and VS and the fact that the latest versions of both have been released quite close to each other.
Now, since we've managed to create our deployment framework regardless and had no issues with it (resorting to command line calls to build solutions with biztalk projects) this wasn't a big issue. until today.
Until now we did not have .net projects that refer to BizTalk projects, but today I've added a proeprty schema, and I've used properties from it in a pipeline component.
to do things properly I try not to hard code the name and namespace of the property but rather take them from the generated class in the compiled property schemas assembly; this, of course, requires that I will add a reference from the pipeline components project (c# assembly) to the BizTalk project (BizTalk assembly).
This broke our deployment script - when we call the MSBuild file of the csproj to build it it works out all the references and tries to build them.
The trouble is that it assumes they are all valid MSBuild files so it calls MSBuild passing it the BTProj file to build, but of course a BTProj file is not a valid MSBuild file so it fails with the error in the subject.
The only way I could avoid this is to remove the reference and hardcode the property names and namespaces in my pipeline component. not the end of the world, but not as elegeant.