"PKDownloadError error 8" upon Catalina update

How do I resolve this? Error was encountered on a 2018 MacBook Air.

I have been pulling my hair out with the same problem over the past few days, and have isolated the PKDownloadError error 8 issue - I was able to solve this via 2 methods:

1. use my iPhone's hotspot as the wifi for the update (note: this is slower AND may be very expensive depending on your cellphone plan)
2. change the DNS settings on my home router to OpenDNS (https://use.opendns.com/), allowing me to use my home internet (faster & cheaper)

First solution:

It is reported that this error occurs during the installation of macOS Catalina if the Internet connection is interrupted or disconnected.

Make sure that the Mac has an active wi-fi or ethernet connection and that the Internet works as expected, and then try to install macOS Catalina again.

Second solution

The Recovery Mode installer of Catalina appears to not be able to properly partition the drive.

Install High Sierra or earlier macOS from Recovery Mode and then upgrade to Catalina or install Catalina (or High Sierra) from a bootable drive.

I was having this error using a Catalina installer on a USB key I made with createinstallmedia. Using this method, the installer shouldn't have to download anything, so a 'download' error didn't make sense.

Purpose: Encrypting and clearing drive in order to return the computer to seller.

Prep work: After encrypting drive, I deleted the old APFS container with Terminal, then I formatted the drive as a single APFS volume named 'Macintosh HD'.

Installation: After beginning the installation, the bar would begin to fill with '3 minutes remaining'. Once it got to about 80%, it said '2 minutes remaining' and it would hold up. A minute or so sitting there and it would give the same error stated above. I retried this a few times.

Fix: I turned off WiFi (completely disconnected from Internet). After doing this, the installation completed as expected.

Suspicions:

The installer app I used was downloaded 3 weeks prior to using it. These do have a short 'expiration' period. Usually resetting the clock to be right after the original download time fixes that issue, but it did not fix it here. Still, communication with Apple's servers or an attempt to download an updated utility could have notified the installer of a discrepancy and forced an error.

My co-worker and I encountered the same thing on our 2018 MacBook Pro (13-inch, Four Thunderbolt 3 Ports) computers.

I found that I needed to restart my computer in Safe Mode (hold Shift key during restart) and then I was able to complete the download and install of Catalina.

My coworker's solution: It turns out that having Cisco AnyConnect installed on the computer interferes with the installation somehow. My coworker used the Cisco AnyConnect Uninstaller to remove the program, ran the installer again successfully, and then re-installed Cisco AnyConnect.