I took time to install an OpenLDAP 2.4.31 package on the 2nd master, and now it all works fine, while the 1st master still runs OpenLDAP 2.4.23:<div>I&#39;ve multi-master replication working in both ways for both backends (data &amp; config).<br>


<div>So, it was not a system problem, although it looked like one.</div><div>I&#39;ll take time to upgrade the 1st server later.<br>Thank you all for your feedback.</div></div><div><br></div>