Having the same question…
In my case, it was due to the absence of the LDAP php module. I installed it via : sudo apt install php5-ldap
(Debian 8.9).
Have the same issue, and got php71-php-ldap installed with no luck. any suggestions?
Centos7, php71, nextcloud 13.0.2
web server needs a reload after installing the php module
I’ve just installed php LDAP module and restarted Apache, but it is still not enabled for me.
php7.3-ldap is already the newest version (7.3.6-1+ubuntu18.04.1+deb.sury.org+1)