Can't add sandbox tester

yes, I'm getting exactly same. Tried Chrome and Safari, different email addresses and other fields - nothing helped.

UPD: solved!

...@bk.ru email isn't accepted, @gmail.com worked. Also you need to use "strong" password (at least 1 capital letter, 1 number and 1 punctuation char). Also you may not use same email twice (even if previously removed)

I am also getting the same error. Any solution for it.

got same error

I got the same error the other day and I solved it.

The problem was also "Please check Error Log, email=********@*****.****", but the issue was with the security of the password. Using the same password as in Apple ID was the solution for me. I suppose it has to have a capital letter and some punctuation mark.

Hope it helps.

That solved it. Thank you!

Not working for me.

This also worked for me. Just add a capital letter and punctuation mark to your password.

great one

Did you able to solve this qsdfazergtezyazer? If yes, then please tell me solution.

You can't use a password similar to the email account name or similar to secure answer

solved it for me too 🙌

I found out that email also matters. I wasn't able to register a @bk.ru email. But @gmail.com worked. Please update your answer

Just adding a full stop to my password solved this "Unknown Error". Cost me a whole bank holiday weekend, thanks for the comments in this thread guys!

Crazy UnknownError! 😟

name+005@domain.com and 24 symbols password solve the problem 😮

for us .. we had to remove the special characters from email. That fixed it for us. We were initially following the guidelines here but seems like they no longer allow this.

https://help.apple.com/app-store-connect/#/dev8b997bee1