Hi… Long story short
Today i got a large win 10 cumulative update, but it failed to install.
A friend of mine got another win 10 previous cumulative update that failed. Clean installing windows made them install successful.
Common thing for both of us: we have comodo installed.
Please… Just for testing sake… Make sure that it is not comodo that causes the updates to fail… Make some tests please. 
Comodo here, just installed all W10 updates
Now I’ve restored windows from my image (it’s basic windows with my drivers - no other software installed)
I have installed windows updates yet again, on my clean system… They worked ! Since i don’t use another security solution, hips, or program that could hinder the update process… Sorry comodo, but I can’t help but suspect your software may have a flaw… I would like some feedback, tests … If possible… I don’t know what could hinder the process… Yet i take into account other possibilities.
I have posted the problem also on ms forums… But their answers are always generic and scriptic.
Don’t really know what to do now.
no comodo doesnt block windows 10 updates
I have all updates installed successfully, Comodo CIS has never been uninstalled.
The issue is on your end, Not CIS
Windows updates are working fine here for Win 10. I am using an updated Insider version.
Do the two computers have the same hardware? Did you try troubleshooting steps for Windows Update?
I reinstalled Windows and the updates seem to work fine now… I guess it must have been one of those updates that MS has retired. I must have had it installed and that may have caused problems. (just guessing)