When updating our project from Unity 4.6.8f1 to 5.2.2f1, we are experiencing missing and broken API on platform Windows Phone 8. It appears that classes that we have been relying upon has had their implementation changed. We have evidence that the same issues arise when updating from 5.0.1f1 to 5.2.2f1. The project are always able to build, and errors will not appear until the application has been deployed and the relevant methods are called. The problematic methods are as follows:

System.IO.FileInfo | OpenRead() : FileStream | Exception: MethodNotFound
System.IO.DirectoryInfo | GetFiles() : FileInto[] | Exeption: MethodNotFound
System.IO.BinaryReader | ReadInt32() : int | End of stream error
System.IO.BinaryReader | ReadInt64() : long | End of stream error
System.IO.BinaryReader | ReadString() : string | End of stream error