Earlier versions of the updater didn’t check this information or accepted what I had done (changing the productVersion) but the new updates didn’t like that.
The updater must check the version, otherwise it couldn't possibly know if the version of the sim supports the add-on.xml, P3D3, for example, supports the add-on.xml method only starting with 3.4 so, it's not enough to "just" check if the Prepar3d.exe is there, but we MUST check the version as well.
Same for P3D4, in order to know if PBR is available, the version must be checked, since it's only available starting with 4.4.
Very briefly, don't edit the version of the .EXE manually. If you have a legacy add-on that doesn't install without changing the version, install the add-on and change it back to the original.