Most likey due to the error with the STEAM version of the far cry 4 map edit program
to fix it, yes you will need to edit your system registry and remove a bad Uplay entry that STEAM created, as well as UNINSTALL, then reinstall the Uplay launcher and your FAR CRY 4 game
here is the link for the ifo on the FC 4 registry fix
(*Note the Uplay only version of FC4,does not have this PROBLEM .only the STEAM version of the game does )
see
https://steamcommunity.com/app/29811...0856106568287/
see also
https://steamcommunity.com/app/29811...4964985644034/
also for other issues you may wish to look into, that may be the cause of your problem ...
please see https://support.ubi.com/en-GB/faqs/0...oubleshooting/
If you still have an issue, Please Contact Ubisoft Support Directly.
you can do so from that above LINKED page .. or here...to open a support ticket / case
https://support.ubi.com
please include your MS info and DX diag files to your support ticket
see this page on how to do that ...
https://support.ubi.com/en-GB/faqs/000026442/
they also have support options via facebook or Twitter in case you have those apps installed ..to check on updates to your support ticket
https://twitter.com/UbisoftSupport
https://www.facebook.com/UbisoftSupport