Getting the same problem.
JST-101691
When the JIRA Administrator had created a "JIRA User" using option "Email a link to the user to set their password", an e-mail was sent to the User. But after clicking the "Set my password" link provided, an authentication window appeared, displaying "Authentication Required. The Server https://asyst-jira.atlassian.net:443 requires a username and password. The server says: Crowd REST End User Authentication".
This authentication window causes Users being unable to Set their Password and preventing new users to login into JIRA.
Steps to reproduce issue:
1. JIRA Administrator create a new "JIRA User", using option "Email a link to the user to set their password".
2. JIRA send an e-mail to new "JIRA User".
3. New "JIRA User" click the "Set my password" button/link provided in the e-mail.
4. "JIRA User" redirected to "Reset Password" page (browser).
5. The page display a basic authentication window "Authentication Required. The Server https://<server-name>.atlassian.net:443 requires a username and password. The server says: Crowd REST End User Authentication"; preventing "JIRA User" to set the password.
Actual result:
"Set my password" functionality cannot be used.
Expected result:
"Set my password" functionality can be used.
Fix confirmed, thank you.