The operation couldn’t be completed. (PKDownloadError error 8.)

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 finally figured it out. I have Cisco Anyconnect VPN installed. Even when that app isn't running, there are some daemons or background agents running and I believe those were blocking access to something the installation app required. I uninstalled Cisco and it installed with no problems.

Summary

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.

The Details

After upgrading to Catalina (from the Catalina beta) I kept having Internet dropouts after my iMac would sleep for a period of time. The only way to get Internet back was to reboot. Shutdown also was taking a long time so I decided to backup my computer (always backup your computer!) and do a clean install of Catalina to determine if the problem was with the Catalina upgrade, software on my system, or perhaps a physical issue.

I started getting this error after trying to to do a clean install of Catalina on my iMac. I entered the Recovery mode, erased the primary drive, and tried to do an install of Catalina. It would run for an hour or more and then I would get this error. I thought this may be related to my connectivity issues so I tried using different wireless networks and dragging an ethernet cable through my house to the router but with no success.

I believe repartitioning the drive was the mistake. Catalina uses a split drive setup where all of the system files are on an inaccessible system partition and the user files are on a separate partition. I believe that by creating a single partition drive the Catalina installer was unable to properly partition the disk and would stall until the Internet connection was finally dropped and the installation failed.

I've now restored to the macOS that came with my iMac, High Sierra, through Recovery mode. I will now do an upgrade to Catalina through the normal methods.

If you can't access a previous version of macOS through Recovery you can create a bootable USB drive that will install macOS High Sierra. Go to https://support.apple.com/en-us/HT201372 for those details. It looks like you can make a bootable Catalina drive but since I am trying to determine if Catalina is the cause of my issue I am going back to High Sierra for a little bit.

Although it wasn’t really showing anywhere, I went through Apple, about my computer and selected to do a software update. It found a security patch. I ran the update, and then I was able to upgrade to the next version. The regular App update did not show any available updates, no messages. Only found it after I did the side check - that I didn’t know existed.

Solving the issue by connecting to a VPN. The installer needs to download data while installing.

I'm finally able to complete the Catalina installation by downloading using different internet connection.

I had the same problem - but later worked for me after I fully shutdown (not a restart), then powered on again - and hit update again.

I am getting the same error as you. I get error 3., not error 8. I have two MBPros. I have a 2018 and a 2019. I successfully installed Catalina on one, the 2018 an upgrade from Mojave. I am trying to install the Catalina upgrade from Mojave on the 2019 MBPro, and I get the error. Similarly as the error 8, mine goes haywire at 13, but also will hang at 2min before crapping out.

Since the first few failures I have done a few things. I have restarted. I am on a different network. I have turned off the firewall, I had semantic virus software that I have turned off, and I have tried again. I get the same error. I am about to see what I need to do to also remove the existing download and then download again from scratch, with all security off - just in case. My 2018 MBPro is personal and does not have the semantic software on it. That is the only difference I can think of, other than I downloaded the original copy from work network.

Thank you! This solved my problem. To be clear, I'm in Mainland China and I assume the installer was trying to download contents blocked by the Great Firewall.

You can have a bootable USB and try option+ R while starting your mac. Shows you the drive and choose the flash drive. You will have no issues.

Did this happen after you remove the "Macintosh HD - Data" volume while doing a fresh installation? Can you recreate this partition and try again?

I am getting the same error code. Any chance you tried doing a clean install by using Macos recovery and erase the internal drive and install Catalina fresh? That’s what I did...or tried. I need to get back to work. =(

I have almost the same problem--PkDownloadError error 3 is what I'm getting. I'm in the U.S. and a home wifi and am trying to upgrade from Mojave. Have tried shutting down and turning back on again and it's not fixing it.

Im having the same problem here. The internet connection is confirmed no problem. Upon 3-5 mins almost finish, the download is stopped with “pkdownloaderror error 8”.

Already shutdown and restart several time.