This error might occur during deployment of BizTalk Project though there are no build errors in the project.
Many blogs suggest that the following key should be there in devenv.config file
<assemblyIdentity name=”EnvDTE” publicKeyToken=
But, this key will be mostly present in all the machines.
In such case, the below steps might resolve the error.
1. If the application is being deployed for the first time, make sure that the Redeploy Flag under the dependencies tab of project properties set to False
2. If the application is already deployed,
i) Stop the deployed application and terminate all instances
ii) Set the Enable Unit Testing Flag under the dependencies tab of project properties set to False and redeploy flag set to true.
Now try to redeploy again.