Hi! I can not install Monterey. I receive followin message message: Installation failed. An error occurred while installing the selected update. My mac iMac: (Retina 5K, 27-inch, 2019, 3.6 GHz 8-Core Intel Core i9, 630GB free space)

Does the OP have an Apple SSD installed? I ask because I had problem with upgrading late 2013 MP to Monterey. Maybe the OP has similar problem.

A while ago I replace the internal Apple SSD with an NVMe drive with adapter in my late 2013 MP. I successfully updated to Big Sur with no problem but could not update to Monterey. Could not even install Monterey on a blank external drive. Then I Googled and it appeared that an Apple internal SSD has to be installed in order to update the firmware and OS boot loader. I installed the original Apple SSD which had Mojave and updated successfully to Monterey. I then booted from my Big Sur NVMe SSD and successfully updated to Monterey. I am typing this from that OS now.

Baronleave wrote:

Hi! I can not install Monterey. I receive followin message message: Installation failed. An error occurred while installing the selected update. My mac iMac: (Retina 5K, 27-inch, 2019, 3.6 GHz 8-Core Intel Core i9, 630GB free space). Any ideas?

If the full installer is sitting in your Application folder: "Install macOS Monterey.app"

Reboot into Safe Boot mode and launch the installer from there

Try the following:

#1 - boot into Safe Mode according to Start up your Mac in safe mode - Apple Support.

NOTE: Safe Mode boot can take up to 3-5 minutes as it's doing the following; 

• Verifies your startup disk and attempts to repair directory issues, if needed

• Loads only required kernel extensions (prevents 3rd party kernel/extensions from loading)

• Prevents Startup Items and Login Items from opening automatically

• Disables user-installed fonts 

• Deletes font caches, kernel cache, and other system cache files

#2 - go to the System/Software Update preference pane and begin the download.

#3 - run the installer from the Safe Mode.

I've had better luck from the Safe Mode because I evidently have some 3rd party software that interferes with the installation.

Try the following:

#1 - boot into Safe Mode according to Start up your Mac in safe mode - Apple Support.

NOTE: Safe Mode boot can take up to 3-5 minutes as it's doing the following; 

• Verifies your startup disk and attempts to repair directory issues, if needed

• Loads only required kernel extensions (prevents 3rd party kernel/extensions from loading)

• Prevents Startup Items and Login Items from opening automatically

• Disables user-installed fonts 

• Deletes font caches, kernel cache, and other system cache files

#2 - go to the System/Software Update preference pane and begin the download.

#3 - run the installer from the Safe Mode.

I've had better luck from the Safe Mode because I evidently have some 3rd party software that interferes with the installation.

Hi Baronleave,

Safe Mode could help, but macOS Monterey only released a couple of hours ago. Apple servers could run into a few issues given the sheer amount of users trying to download macOS Monterey.

I have same problem/error message on my late 2013 MacPro from both normal startup and startup to safe mode.

When I try to install on a blank/newly formatted external USB disk I get error message that "The operation could not be completed (PK download error 15)". I could not find that error message via Google.

I didn't see that in your original post:

🤣🤣🤣

As I originally stated I tried downloading and installing from normal startup and then deleted that installer and startup in Safe mode and redownloaded and tried install with same error messages.