MacBook Pro failing to connect to network after upgrading to version15.0

Launch a browser and enter this easy to remember all-numeric IP address:

1.1.1.1

in the address bar, and press return.

If you get the CloudFlare** splash page, your internet is working, but DNS lookup may not be working.

**CloudFlare is NOT part of the solution, they just own the easiest to remember all-numeric IP Address.

Settings > network > Wi-Fi > your specific connection (Details) > TCP/IP

should look like this older one:

...

what is the IP address shown, and is there any errors message with it?

Those setting indicate you should have a good connection.

Change configure IPv6 from 'automatically' to 'Link-local only'.

Close the window ask save changes.

If the results are still that same error message, try with Safari, because your browser appears to be interfering with normal operation.

what status is shown in

System preferences > network

click on (details). if you have a regular IP address, (not self-assigned IP address) then you Have an internet connection.

if no joy, try with Safari