If you see “There was an error. You entered an invalid username or password”, then:
- verify the mailbox name has been entered correctly;
- verify the chosen domain is correct;
- be sure the password is entered in the correct language and that Caps Lock is off.
To recover your password, tap “I forgot my password”.
Please note that due to a recent change in Yahoo security settings there might be problems with @yahoo.com accounts. If you use such a mailbox and encountered difficulties adding is to the application, or sending and receiving messages in it, go to «Account security» settings and switch “Allow apps that use less secure sign in” into the ON position.