diff --git a/scripts/docker/install/rootless/rootless_docker.sh b/scripts/docker/install/rootless/rootless_docker.sh
index c54ec54..3565ab4 100755
--- a/scripts/docker/install/rootless/rootless_docker.sh
+++ b/scripts/docker/install/rootless/rootless_docker.sh
@@ -38,7 +38,10 @@ installDockerRootless()
         installed_version=$(slirp4netns --version 2>/dev/null | head -n1 | awk '{print $3}')
         isSuccessful "slirp4netns ${installed_version:-installed} is ready"
 
-        if [[ $(lsb_release -rs) == "10" ]]; then
+        # Debian 10 only. Use the values detectOS already resolved from /etc/os-release
+        # instead of shelling out to lsb_release, which isn't installed by default on
+        # minimal Ubuntu/Debian images (and would otherwise just error to stderr here).
+        if [[ "$OS_TYPE" == "Debian" && "$OS_VERSION" == "10" ]]; then
             ((menu_number++))
             echo ""
             echo "---- $menu_number. Updating the sysctl file for Updating Debian 10."
diff --git a/scripts/os/install/ubuntu.sh b/scripts/os/install/ubuntu.sh
index 7b24420..6081eb6 100755
--- a/scripts/os/install/ubuntu.sh
+++ b/scripts/os/install/ubuntu.sh
@@ -22,19 +22,30 @@ installDebianUbuntu()
         fi
 
         if checkIfOSUpdateShouldRun; then
-            installed_apps="apt install curl dialog pv wget git zip htop sqlite3 pv sshpass rsync acl apache2-utils inotify-tools jq p7zip*"
-
             isNotice "Installing System Updates... this may take a while."
             if [[ "$OS_TYPE" == "Debian" ]]; then
                 export DEBIAN_FRONTEND="noninteractive"
             fi
 
-            local result; result=$(DEBIAN_FRONTEND=noninteractive APT_KEY_DONT_WARN_ON_DANGEROUS_USAGE=1 $priv apt update -qq 2>&1 && DEBIAN_FRONTEND=noninteractive APT_KEY_DONT_WARN_ON_DANGEROUS_USAGE=1 $priv apt install sudo -yqq 2>&1 && $priv apt-get autoclean 2>&1)
+            local result; result=$(DEBIAN_FRONTEND=noninteractive APT_KEY_DONT_WARN_ON_DANGEROUS_USAGE=1 $priv apt-get update -qq 2>&1 && DEBIAN_FRONTEND=noninteractive APT_KEY_DONT_WARN_ON_DANGEROUS_USAGE=1 $priv apt-get install sudo -yqq 2>&1 && $priv apt-get autoclean 2>&1)
             checkSuccess "Updating System Operating system."
 
-            local result; result=$(DEBIAN_FRONTEND=noninteractive APT_KEY_DONT_WARN_ON_DANGEROUS_USAGE=1 $priv apt update -qq 2>&1)
+            local result; result=$(DEBIAN_FRONTEND=noninteractive APT_KEY_DONT_WARN_ON_DANGEROUS_USAGE=1 $priv apt-get update -qq 2>&1)
             checkSuccess "Running application update"
 
+            # 7-Zip changed package name: Debian 13 and Ubuntu 24.04+ ship `7zip`, older
+            # releases ship `p7zip-full`. Resolve against the freshly-updated package
+            # lists rather than relying on a `p7zip*` glob — that only still matches on
+            # new releases because `7zip` happens to declare `Provides: p7zip`.
+            # Match on a real package stanza, not just apt-cache's exit status — it
+            # returns 0 with empty output for virtual/provided-only names.
+            local sevenzip="p7zip-full"
+            if apt-cache show 7zip 2>/dev/null | grep -q .; then
+                sevenzip="7zip"
+            fi
+
+            installed_apps="apt-get install curl dialog pv wget git zip htop sqlite3 sshpass rsync acl apache2-utils inotify-tools jq $sevenzip"
+
             local result; result=$(DEBIAN_FRONTEND=noninteractive APT_KEY_DONT_WARN_ON_DANGEROUS_USAGE=1 $priv $installed_apps -yqq 2>&1)
             checkSuccess "Installing system applications"
         else