Hello, not sure if I understand it correctly. But in case of DMQ, you need to have both proxies at least on the same major version (5.5.x), replication will not work from 5.4.x to 5.5.x for example. So you need to update both proxies the same time. Cheers, Henning -- Henning Westerholt – https://skalatan.de/blog/ Kamailio services – https://gilawa.com<https://gilawa.com/> From: satyaprakash ch &lt;chiramchetty.satyaprakash(a)gmail.com&gt; Sent: Donnerstag, 6. April 2023 09:39 To: Kamailio (SER) - Users Mailing List &lt;sr-users(a)lists.kamailio.org&gt; Subject: [SR-Users] Re: issue in kamailio of udp Here I need to mention is, I was maintaining the 2 proxies with Kamailio version 5.4.7, Then I have only upgraded a single proxy to 5.5.5, Is there any compatibility for the version change of a single proxy server that makes the issue? Because the 2 proxy servers are maintained with DMQ, Awaiting any reply for this..! On Wed, Apr 5, 2023 at 11:23 PM satyaprakash ch <chiramchetty.satyaprakash@gmail.com<mailto:chiramchetty.satyaprakash@gmail.com>> wrote: Hi, I had upgraded Kamailio from 5.4.7 to 5.5.5, Then I restarted the Kamailio service. After upgradation im getting the below error, /usr/local/sbin/kamailio[21754]: ERROR: <core> [core/udp_server.c:596]: udp_send(): sendto(sock, buf: 0x7f7502289200, len: 61012, 0, dst: (10.122.45.189:5080<http://10.122.45.189:5080>), tolen: 16) - err: No buffer space available (105) /usr/local/sbin/kamailio[21754]: ERROR: tm [../../core/forward.h:231]: msg_send_buffer(): udp_send failed /usr/local/sbin/kamailio[21754]: ERROR: tm [uac.c:678]: send_prepared_request_impl(): Attempt to send to precreated request failed ERROR: tm [../../core/forward.h:231]: msg_send_buffer(): udp_send failed ERROR: tm [uac.c:678]: send_prepared_request_impl(): Attempt to send to precreated request failed Anyone have any idea on this errors.