Hossein Ahmadian was able to replicate it on https://mysql.test.mattermost.com/.
Steps:
1.Send invite by email to a guest not already on the server
2. Open the link in incognito
3. Create an account via the SAML option
4. You will be presented to the login page (Not sure if that's intended functionality or not ... but my gut feeling says its a bug)
5. Press login via SAML (Onelogin in the case of mysql.test)
6. :boom2: You're presented with this page (attached) which says the sign up link does not appear to be valid.
See description for reproduction steps
Issue repros with this release test (regression):
1. While not logged in on the server, open URL to a public channel such as https://mysql.test.mattermost.com/zzz-qa/channels/saml-test
2. On login page, click button to log in using SAML
3. Enter valid SAML credentials for a user who does not yet have an account on the server, submit
Expected: Account is created, user is viewing tutorial. After dismissing tutorial user is viewing the channel the link was for.
Observed: Error page `Channel Not Found. The channel you're requesting is private or does not exist. Please contact an Administrator to be added to the channel.`
NOTE: From that page, the `Back to Town Square` link does indeed take the user to Town Square and the tutorial displays, so the user's account was created. (But the channel the URL was for was not joined.)
I believe what you have stated above should be another bug ticket as it’s not related to the bug mentioned above. I looked into the bug you’ve posted and that is something separate from the bug experienced in this ticket.
Verified working as described, added test case for this scenario T-3304 (linked above). The scenario I had described in a comment was also working as expected on re-running through the SAML regression tests, so no additional issues were found or are outstanding. Closing.
Re-opening and putting back into Resolved to verify the v5.25 backport. Adding label `done-5.26` to indicate that this has been verified on the current release.
Also verified on prev.test on v5.25.3-rc1 that the guest invite can be completed by user signing up via OKTA. Closing ticket.