Repeatedly failed windows updates: Cumulative for Windows 10 Version 1703 x64 KB4056891 and Windows
As for the first case, KB4056891, Windows support states:
|Due to an issue with some versions of Anti-Virus software, this fix is only being made applicable to the machines where the Anti virus ISV has updated the ALLOW REGKEY.
Contact your Anti-Virus AV to confirm that their software is compatible and have set the following REGKEY on the machine
Can this be solved by you?