Cant install macOS Catalina

Hi may9901,

Thanks for reaching out in Apple Support Communities. I understand that you're encountering an error regarding your internet connection when trying to complete the macOS Catalina install. I see you've tried to install twice and continue to see the error and the other Mac in the household didn't have an issue. I know it's important to keep your devices up-to-date; I'd like to help. First, I'd recommend trying to install the upgrade using safe mode: Use safe mode to isolate issues with your Mac

If the installation fails again, try with a test user account: How to test an issue in another user account on your Mac

I'd also suggest reviewing the information in the resource indicated in your screenshot if you haven't already, although it mentions Mojave, the steps should apply to a Catalina install as well: If error 'com.apple.OSInstallerSetup.error Code=551' occurs when installing macOS

Let me know what you find.

Best Regards.

It seems like you might have a network issue, try to confirm if SOCKS proxy turned on. You can check that by going system preferences>network> wi-fi (or ethernet)> advanced> proxies > and untick SOCKS proxy. While on the same menu I also would advise you to select the option "TCP/IP" and click on "renew DHCP lease"

I also would advise you to try:

https://support.apple.com/en-gb/HT202663

https://support.apple.com/en-gb/HT201974

and last but not least to try to do safe mode and to reset smc, here's the articles for that:

https://support.apple.com/en-gb/HT201262

https://support.apple.com/en-gb/HT201295