Can't Change / Remove Apple ID Notification Email Address

This message seems to be appearing in all kinds of situations in the past few days. The only common element is to try another browser or perhaps simply try again.

Related discussions:

every time I tried to create an app-speci… - Apple Community

"Someone in another post said to use a different browser (not Safari or whichever one you normally use). That worked for me."

"Use a computer to generate the App specific passwords. Don't use Safari or Chrome. I got it to work using Firefox on my Mac."

"the Chrome browser works for me."

Can't change Apple ID - Apple Community

"OK it just worked. No idea what was going on before. Thanks for the help anyway!"

Refer to doing this in this support article About your Apple ID email addresses - Apple Support

However, you posted a notification I have only ever seen in a few posts and only in the past few says. It appears to me to be something completely erratic since it appears in various contexts. Since you posted the message I thought that was causing this problem and I posted all I knew about it. So if the method in the article does not work and is producing that message then there may be something else that is causing an issue and you need to resolve that. As I said, it may be tricky because that message is completely new to me and seems to appear under different circumstances with the only common element being web browsers.

Repeating the procedure using Firefox, not Safari, solved the issue for me.