hi,
i have downloaded UE4 from a computer and copied it to another one (pf/epic games folder).
the problem is that the engine version is not recognized by the launcher,however i can run theeditor directly (UE4Editor.exe)
how to fix this please ?
I had a similar issue the other day but not due to moving the engine to a new computer or anything. The launcher was giving me an unrecognised version error.
My fix was to add ‘-http=wininet’ to the target path in my launcher shortcuts target. Basically right click on the desktop shortcut to the launcher, click Properties, click the Shortcut tab and make the Target string look similar to this:
This may not help but it solved a similar error for me albeit under different circumstances.
well, it was really simple 
just clicked the install button, it did some verifications/small download about (15min)
and voila !
now i have 4.7.2 version correctly recognized