We have two moodle installation's running on 3.4+ the one in question has been updated today and I have come across an issue with the sso redirect to the standard login page.
When using a browser that's not IE (ie brave, edge,firefox) the SSO does as expected and falls back to go to the login page, but then goes to a 404 page. This is because the URL its redirecting to is incorrect thus throwing up the 404 error.
I have had a look in the php code and cannot see anywhere its getting the extra /login/1 information from, and all looks correct.
Its odd as our other site is working properly and both are configured the same.
Ie fastpath is on and works if using internet explorer but anything else throws the 404 error due to the incorrect url
Both are running PHP 7.1.10
MySQL 5.7.7
and moodle 3.4 build 20171201
Any ideas on what I can check would be greatly appreciated.