diff -Nru frr-8.1/debian/changelog frr-8.1/debian/changelog
--- frr-8.1/debian/changelog	2022-10-05 16:35:26.000000000 +0000
+++ frr-8.1/debian/changelog	2022-10-28 14:38:34.000000000 +0000
@@ -1,3 +1,11 @@
+frr (8.1-1ubuntu1.3) jammy; urgency=medium
+
+  * d/frr.postinst: don't change log ownership if the syslog user
+    doesn't exist. Thanks to Alessandro Ratti
+    <alessandro.ratti@exoscale.ch> for the fix (LP: #1991812).
+
+ -- Andreas Hasenack <andreas@canonical.com>  Fri, 28 Oct 2022 11:38:34 -0300
+
 frr (8.1-1ubuntu1.2) jammy-security; urgency=medium
 
   * SECURITY UPDATE: DoS via out-of-bounds read
diff -Nru frr-8.1/debian/frr.postinst frr-8.1/debian/frr.postinst
--- frr-8.1/debian/frr.postinst	2022-07-19 20:36:23.000000000 +0000
+++ frr-8.1/debian/frr.postinst	2022-10-28 14:38:34.000000000 +0000
@@ -50,26 +50,28 @@
 # fix logging for Ubuntu, which does not run rsyslog as root (LP: #1958162),
 # and upgrades from quagga (what the block above used to do also for /var/log)
 
-# frr user was created above, this really shouldn't fail
-frruid=`getent passwd frr | cut -d : -f 3`
-frrgid=`getent group frr | cut -d : -f 3`
+if getent passwd syslog > /dev/null; then
+    # frr user was created above, this really shouldn't fail
+    frruid=`getent passwd frr | cut -d : -f 3`
+    frrgid=`getent group frr | cut -d : -f 3`
 
-find \
-    /var/log/frr \
-        \( -uid 0 -o -uid $quaggauid -o -uid $frruid \) -a \
-        \( -gid 0 -o -gid $quaggauid -o -gid $frrgid \) | \
-    while read filename; do
+    find \
+        /var/log/frr \
+            \( -uid 0 -o -uid $quaggauid -o -uid $frruid \) -a \
+            \( -gid 0 -o -gid $quaggauid -o -gid $frrgid \) | \
+        while read filename; do
 
-    # don't chown anything that has ACLs (but don't fail if we don't
-    # have getfacl)
-    if { getfacl -c "$filename" 2>/dev/null || true; } \
-        | egrep -q -v '^((user|group|other)::|$)'; then
-        :
-    else
-        chown syslog:adm "$filename"
-        chmod o-rwx "$filename"
-    fi
-done
+        # don't chown anything that has ACLs (but don't fail if we don't
+        # have getfacl)
+        if { getfacl -c "$filename" 2>/dev/null || true; } \
+            | egrep -q -v '^((user|group|other)::|$)'; then
+            :
+        else
+            chown syslog:adm "$filename"
+            chmod o-rwx "$filename"
+        fi
+    done
+fi
 
 # fix misconfigured vtysh.conf & frr.conf ownership caused by config save
 # mishandling in earlier FRR (and Quagga) versions