You should raise this issue with IPM team, there are some work related to python, where it happens, and it could be related to intersystems-irispython official driver, which tend to fail randomly with segmentation fault, and this error most probably is comming from Python

A bit hackish way

{
  while IFS= read -r line; do
    echo 'write *27,"[1F",$namespace,">", "'$(echo $line | sed "s/\"/\"\"/g" )'",*27,"[1F"'
    printf '%s\n' "$line"
  done
} <<'EOF' | iris session iris
write $zv
write !,"hello ", $username,!
zn "%sys"
halt
EOF

and output

$ bash test.sh 

Node: e91a00f6512e, Instance: IRIS

USER>write $zv
IRIS for UNIX (Ubuntu Server LTS for ARM64 Containers) 2026.1.0L (Build 193U) Tue Jan 6 2026 01:46:47 EST
USER>write !,"hello ", $username,!

hello irisowner

USER>zn "%sys"

%SYS>halt

Hi! I’m in for a random coffee chat ☕
Location: Australia, Melbourne
Availability: Mon–Fri, 11:00–16:00
Happy to chat