Hello, Since I upgraded to 3.2.2-cznic.1~bullseye, my scripts using knsupdate fails, on every machine they run on. I can reproduce this with gdb, here is the trace I get in this case : Starting program: /usr/bin/knsupdate -k /etc/letsencrypt.sh/hooks/tsig.key /tmp/tmp.17EBRdeI8j [Thread debugging using libthread_db enabled] Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1". Program received signal SIGSEGV, Segmentation fault. 0x000055555556161c in net_send (net=net@entry=0x7ffffffcbb80, buf=0x555555592a10 "\345\327(", buf_len=196) at utils/common/netio.c:587 587 utils/common/netio.c: No such file or directory. (gdb) where #0 0x000055555556161c in net_send (net=net@entry=0x7ffffffcbb80, buf=0x555555592a10 "\345\327(", buf_len=196) at utils/common/netio.c:587 #1 0x000055555555adee in pkt_sendrecv (params=params@entry=0x7ffffffcbdd0) at utils/knsupdate/knsupdate_exec.c:456 #2 0x000055555555ba01 in cmd_send (lp=<optimized out>, params=0x7ffffffcbdd0) at utils/knsupdate/knsupdate_exec.c:851 #3 0x000055555555b3e6 in knsupdate_process_line (line=line@entry=0x5555555755e0 "send", params=params@entry=0x7ffffffcbdd0) at utils/knsupdate/knsupdate_exec.c:498 #4 0x000055555555b5ed in knsupdate_process_line (params=0x7ffffffcbdd0, line=0x5555555755e0 "send") at utils/knsupdate/knsupdate_exec.c:486 #5 process_lines (params=params@entry=0x7ffffffcbdd0, input=input@entry=0x5555555910f0) at utils/knsupdate/knsupdate_exec.c:527 #6 0x000055555555bd3e in knsupdate_exec (params=params@entry=0x7ffffffcbdd0) at utils/knsupdate/knsupdate_exec.c:575 #7 0x0000555555559dc9 in main (argc=<optimized out>, argv=0x7fffffffe548) at utils/knsupdate/knsupdate_main.c:35 The nsupdate script (/tmp/tmp.17EBRdeI8j) is here (with truncated TXT) : server 10.42.42.21 zone durel.eu. origin durel.eu. ttl 600 add _acme-challenge.ns.durel.eu. 600 in TXT "qLH_KkbQ_IUVr[...]7rs-iUE" send quit As I can reproduce this with any tsig key, I can provide a core if you need it. --