So, I upgraded my site to 3.5 and have noticed some new behavior which is pretty frustrating.
When I load my students into LDAP, I leave their email address field empty. This has always worked really well in the past because Moodle prompts them to fill in their email on first log in and I get a current email address for them. But now, while Moodle still prompts them to fill it in, it will not allow the update to go through (even when I try as the site admin), throwing an error in the apache logs of [AUTH LDAP] Failed to update LDAP with non-existent field ('mail'). If I go into the LDAP user and throw some random letter in the email field, then it will allow the students to update it.
It appears that the LDAP plugin is now requiring the field to have data in it already to recognize it as a fillable field. We have not changed anything on the LDAP server so I have to presume that this was maybe put into the 3.5 ldap plugin.
Iñaki, can you confirm if this expected behavior and if it is a new feature/bug?