Issue
I tried to log in to Heroku by running the Heroku CLI command
heroku login
The browser window shows "IP address mismatch" and I cannot proceed further.
Resolution
As described in our changelog at https://devcenter.heroku.com/changelog-items/1873, the platform requires that the IP address of both the CLI and web browser align.
This means that you will need to have the same proxy setup for both the CLI and the browser used to authenticate. You'll need to configure the web proxy in the CLI with the https_proxy option. You may need to restart your browser once these configurations are made for the changes to take effect.
"IP address mismatch" is a known issue when using iCloud Private Relay on a Mac and disabling it would resolve the error.