I developed an application with VS2010 and a setup deployment with IS Limited Edition. The application provides some data in a XML file, which is installed in the same folder. If the app was making changes in the XML file, this was saved in virtualStore.
I use now VS2015 and Wix Toolset. The application can be compiled and I was able to code a WXS File. The new built MSI install the app and all seems ok. But now the app cannot access the XML file. The access is denied. I tried to compare both MSI with Orca, but don't see something noticeable. I'm not sure, if this is a problem of setup or of the application itself.
edit
If I copy the "old" EXE file in the new installation, the application can access the XML file.
Thank you for help and hints
If a program appears to be from before Windows Vista, is running as a limited user, and attempts to write to certain machine-only locations, Windows may redirect its access to the virtual store as part of a backwards compatibility shim. If the program does not appear to be from before Windows Vista, no redirection is performed.
I believe Windows detects whether a program appears to be from before Windows Vista by reading its manifest for supported platforms - the supportedOS elements in the application manifest. My guess is the change in your toolchain from VS 2010 to VS 2015 has resulted in this element being added to your application's manifest (Windows XP is past its supported lifetime and thus Visual Studio 2015 can implicitly assume you are supporting at least Vista).
You may be able to override the manifest, but really you should fix your program to not attempt to write to per-machine locations. Ideally you should use a location such as the LocalAppData folder, although for backwards compatibility there may be benefits to at least reading the old file from the Virtual Store.