Issue Summary

The issue happens for some customers during the SAML SSO login flow. After providing the username and clicking the Continue button, it doesn't redirect to the IDP login page; instead, there is a spinning wheel that keeps spinning

Steps to Reproduce

Prerequisite - Atlassian account has been enforced with SAML SSO via the authentication policy

1. Open a Chrome Incognito Window
2. Navigate to https://id.atlassian.com
3. Provide username
4. Click the big blue button Continue

Note - Issue can't be replicated from our end.
 

Expected Results

• It will redirect to the IDP login page to allow the user to authenticate via SAML

Actual Results

• It doesn't redirect to the IDP login page; instead, there is a spinning wheel that keeps spinning
• We can see "Provisional headers are not shown" warning message for POST requests to recaptcha.net and requests to recaptcha.net were unsuccessful at the beginning of the login process - 0 content downloaded. For example:

• Manually blocked the requests to recaptcha.net from web browser - developer tools, and then try the SAML SSO login again, and we can replicate the same issue
• Affected users are from China mainland
• Confirmed that recaptcha.net is not blocked by the network

Workaround

IDP-initiated login would be the possible option for SAML SSO, if SAML SSO is required; otherwise, customer will need to log in via Atlassian credentials or any possible social logins.
If SAML SSO is necessary, the customer will need to ensure recaptcha.net will not be blocked by their network