"PKDownloadError error 8" upon Catalina update

In my case I had to change my firewall settings in my router from average to low.

I had this same PKDownload error in November 2020 when trying to d/l Big Sur. I spent close to 5 hours with Apple Support, being bumped up to the Apple Senior Enginer level of help. I was told that this error is a Network Error. Long story short, we never solved the problem, but do read on.
I go the PK error on my 2015 iMac running Catalina. I then went to my wife's brand new 2019 MB Pro: same download error.
The only thing in common between the two Macs was the router and so, on a hunch, took the MB Pro next door, logged onto my neighbor's WiFi, and successfully downloaded and installed Big Sur.

Just solve this problem.

Step 1 Backup just in case. You can backup your important files to the cloud or everywhere you prefer.

Step 2 Move the downloaded installer to the Trash.

Step 3 Shut down your Mac.

Step 4 Turn it on and immediately press and hold these four keys together: Option, Command, P, and R. You can release the keys after about 20 seconds, during which your Mac might appear to restart. On Mac computers that play a startup sound, you can release the keys after the second startup sound. [This is NVRAM reset!]

Step 5 Go to the App Store, find Catalina, and download again.

Step 6 Follow the instruction and wait for like 30 minutes. Now you should get the new macOS.

If the error still pops up, change to another network connection.

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)

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.

For what it is worth, this had to have been a content filter issue for me. I have prepped 2 new Macs, a 2019 Air and a 2019 MBP, and got this error on both my wired and wireless networks.

I was able to plug the same devices on edge connections (read: less restrictive internet connections) and the install went through with no issue.

If I had time, I would try to see what resource was being blocked, but at least for now, I know what was causing the error and how to get past it.

Austin -Network Administrator @ a large 9-12 Educational Institution

I faced the same error with a brand new installation, I don't know about your case. You can reboot your mac then hold the "option key". You will see a select box to select a wi-fi network after that the recovery by the internet will start. That way you can install a version before Catalina. In my case was Sierra. Then after the new installation, you can update to Catalina!

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.