List of Issues updating to MacOS 10.11.x (El Capitan)

I just updated the first Mac in our family to El Capitan and thought it would be useful to create a list of the update issues I (and others) encountered.
That would make it easier to troubleshoot and correct any problems that occurred during the upgarde.
I would encourage anyone who has run into upgrade issues going to El Capitan to post them here.
I'll start with one of my own:

1. Problem is getting to websites in general. Browser has difficulty resolving the URL.
Turns out that when upgrading from 10.9 to 10.11 (which was the upgrade on this specific Mac), the DNS server addresses were not transferred.
Only a single DNS server showed up in Network preferences and it was the ISP DNS server as far as I can tell.
I used to have two ISP DNS servers and the two google DNS servers in Network preferences.
Adding the google servers 8.8.8.8 and 8.8.4.4 solved that issue.
As a side note - I'm not crazy about using google for anything because of their tracking.
Anyone have experience with other DNS servers, like the ones from "Level 3"?

209.244.0.3
209.244.0.4
4.2.2.1
4.2.2.2
4.2.2.3
4.2.2.4

2. Second issue will go here. Updated yesterday and so far I have not come across another issue

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