[Koha] LDAP (Active Directory) Authentication broken after an upgrade to 3.12

[Mesfin Teshome]

Dear all,
Active directory authentication in Koha is no more working after an upgrade from Koha 3.10 to Koha 3.12. Here is my koha-conf.xml file 
 
<ldapserver id="ADserverFQDN" listenref="ADserverFQDN">

 <hostname>ldap://ADserverFQDN:389</hostname>
 <base>DC="domain",DC="domain"</base>
 <user>cn="######",DC="domain",DC="domain"</user>
 <pass>########</pass>
 <replicate>1</replicate>
 <update>1</update>
 <auth_by_bind>1</auth_by_bind>
 <principal_name>%s@"domain"</principal_name>
 <mapping>
<firstname    is="givenname"></firstname>
<surname      is="sn"></surname>
<address      is="postaladdress"></address>
<city       is="l"></city>
<zipcode      is="postalcode"></zipcode>
<branchcode   is="branch">CPL</branchcode>
<userid       is="samAccountName"></userid>
<password     is="userpassword"></password>
<email        is="mail"></email>
<categorycode is="employeetype"></categorycode>
<phone        is="telephonenumber"></phone>
 </mapping> 
 </ldapserver>

What is this update about "7973	Allow for new type of LDAP authentication"? My koha-conf.xml was working fine before the upgrade.

Mesfin