Same here:

P2421 on fully patched W10Pro

Thanks for your response.

I know it can't be due to anything on my system, because it's a super clean setup with absolutely ZERO issues.

And this is what happens when I rightclick on "P2421.inf" and choose "Install":

After that there is nothing to find in any eventlog.

I'm getting the same error message, but in English and not in German (because I have an English OS install...)

The issue is the driver is not digitally signed. DELL, please fix the drivers!

I don't think the lack of a digital signature is the issue here. I've installed unsigned drivers countless times...

If you look at the dialog from which you created a screenshot, you will notice that the "Next" button is active. That would not be the case if Windows would actually REJECT installation.

@Ralf G. R. Bergs  @rowwt  @KOPFteam Hey there, I am having the same issues. Did anyone manage to find a solution or workaround? 

Nope, I continue to fail to install the driver...

The Christmas may come earlier :)...

I've had a conversation with dell support. They'll look into the issue.

"Great. I appreciate your expertise. Considering the steps which you/we have already performed I will have to get this reviewed by our Product Engineering team as this may require their inputs. I will prepare a complete summary and forward the same to our product engineering team. This will require 1-2 business days to get back to you with a resolution"