diff --git a/install_proxmenux.sh b/install_proxmenux.sh
index bf30995b..10d12cbe 100755
--- a/install_proxmenux.sh
+++ b/install_proxmenux.sh
@@ -335,6 +335,31 @@ update_config() {
     fi
 }
 
+# apt output goes to a temporary file: shown only when the command fails, so
+# the reader sees why. Non-interactive, because a hidden prompt would hang.
+APT_ERROR_LOG=""
+run_apt() {
+    APT_ERROR_LOG=$(mktemp /tmp/proxmenux-apt.XXXXXX)
+    if DEBIAN_FRONTEND=noninteractive apt-get "$@" >"$APT_ERROR_LOG" 2>&1; then
+        rm -f "$APT_ERROR_LOG"
+        APT_ERROR_LOG=""
+        return 0
+    fi
+    return 1
+}
+
+show_apt_error() {
+    [ -n "$APT_ERROR_LOG" ] && [ -f "$APT_ERROR_LOG" ] || return 0
+    tail -n 15 "$APT_ERROR_LOG" | sed 's/^/    /'
+    rm -f "$APT_ERROR_LOG"
+    APT_ERROR_LOG=""
+}
+
+discard_apt_error() {
+    [ -n "$APT_ERROR_LOG" ] && rm -f "$APT_ERROR_LOG"
+    APT_ERROR_LOG=""
+}
+
 show_progress() {
     local step="$1"
     local total="$2"
@@ -680,17 +705,19 @@ install_normal_version() {
     show_progress $current_step $total_steps "Installing basic dependencies."
 
     msg_info "Refreshing apt cache..."
-    if apt-get update -y; then
+    if run_apt update -y; then
         msg_ok "apt cache refreshed."
     else
         msg_warn "apt cache refresh failed; checking available packages."
+        show_apt_error
     fi
 
     msg_info "Installing jq..."
     if ! command -v jq > /dev/null 2>&1; then
-        if apt-get install -y jq && command -v jq > /dev/null 2>&1; then
+        if run_apt install -y jq && command -v jq > /dev/null 2>&1; then
             update_config "jq" "installed"
         else
+            discard_apt_error
             local jq_url="https://github.com/jqlang/jq/releases/download/jq-1.7.1/jq-linux-amd64"
             if wget -q -O /usr/local/bin/jq "$jq_url" 2>/dev/null && chmod +x /usr/local/bin/jq; then
                 if command -v jq > /dev/null 2>&1; then
@@ -718,10 +745,11 @@ install_normal_version() {
         # dpkg-query for the EXACT package — `dpkg -l | grep -qw python3`
         # falsely matches `python3-pip`. Issue #205.
         if ! dpkg-query -W -f='${Status}' "$pkg" 2>/dev/null | grep -q "ok installed"; then
-            if apt-get install -y "$pkg"; then
+            if run_apt install -y "$pkg"; then
                 update_config "$pkg" "installed"
             else
                 msg_error "Failed to install $pkg. Please install it manually."
+                show_apt_error
                 update_config "$pkg" "failed"
                 return 1
             fi
diff --git a/install_proxmenux_beta.sh b/install_proxmenux_beta.sh
index ed0d5a29..b1388b7b 100644
--- a/install_proxmenux_beta.sh
+++ b/install_proxmenux_beta.sh
@@ -139,6 +139,31 @@ msg_title() {
     echo -e "\n"
 }
 
+# apt output goes to a temporary file: shown only when the command fails, so
+# the reader sees why. Non-interactive, because a hidden prompt would hang.
+APT_ERROR_LOG=""
+run_apt() {
+    APT_ERROR_LOG=$(mktemp /tmp/proxmenux-apt.XXXXXX)
+    if DEBIAN_FRONTEND=noninteractive apt-get "$@" >"$APT_ERROR_LOG" 2>&1; then
+        rm -f "$APT_ERROR_LOG"
+        APT_ERROR_LOG=""
+        return 0
+    fi
+    return 1
+}
+
+show_apt_error() {
+    [ -n "$APT_ERROR_LOG" ] && [ -f "$APT_ERROR_LOG" ] || return 0
+    tail -n 15 "$APT_ERROR_LOG" | sed 's/^/    /'
+    rm -f "$APT_ERROR_LOG"
+    APT_ERROR_LOG=""
+}
+
+discard_apt_error() {
+    [ -n "$APT_ERROR_LOG" ] && rm -f "$APT_ERROR_LOG"
+    APT_ERROR_LOG=""
+}
+
 show_progress() {
     echo -e "\n${BOLD}${BL}${TAB}Installing ProxMenux Beta: Step ${1} of ${2}${CL}"
     echo
@@ -611,17 +636,19 @@ install_beta() {
     show_progress $current_step $total_steps "Installing system dependencies"
 
     msg_info "Refreshing apt cache..."
-    if apt-get update -y; then
+    if run_apt update -y; then
         msg_ok "apt cache refreshed."
     else
         msg_warn "apt cache refresh failed; checking available packages."
+        show_apt_error
     fi
 
     msg_info "Installing jq..."
     if ! command -v jq > /dev/null 2>&1; then
-        if apt-get install -y jq && command -v jq > /dev/null 2>&1; then
+        if run_apt install -y jq && command -v jq > /dev/null 2>&1; then
             update_config "jq" "installed"
         else
+            discard_apt_error
             local jq_url="https://github.com/jqlang/jq/releases/download/jq-1.7.1/jq-linux-amd64"
             if wget -q -O /usr/local/bin/jq "$jq_url" 2>/dev/null && chmod +x /usr/local/bin/jq \
                && command -v jq > /dev/null 2>&1; then
@@ -643,10 +670,11 @@ install_beta() {
         # dpkg-query for the EXACT package name — `dpkg -l | grep -qw python3`
         # falsely matches `python3-pip`. Issue #205.
         if ! dpkg-query -W -f='${Status}' "$pkg" 2>/dev/null | grep -q "ok installed"; then
-            if apt-get install -y "$pkg"; then
+            if run_apt install -y "$pkg"; then
                 update_config "$pkg" "installed"
             else
                 msg_error "Failed to install $pkg. Please install it manually."
+                show_apt_error
                 update_config "$pkg" "failed"
                 return 1
             fi
diff --git a/scripts/global/common-functions.sh b/scripts/global/common-functions.sh
index ef4ed059..dd95e9bf 100644
--- a/scripts/global/common-functions.sh
+++ b/scripts/global/common-functions.sh
@@ -114,16 +114,27 @@ cleanup_duplicate_repos_pve9() {
     }
 
     # Helper: back up a file once before modifying, so an accidental
-    # comment-out is always recoverable next to the original.
+    # comment-out is always recoverable. Outside sources.list.d: apt reads
+    # every file there and warns about each copy on every update.
+    local backup_dir="/var/backups/proxmenux/apt"
     _backup_once() {
         local file="$1"
         [[ -f "$file" ]] || return 0
         local ts backup
         ts=$(date +%Y%m%d_%H%M%S)
-        backup="${file}.proxmenux-backup.${ts}"
+        mkdir -p "$backup_dir"
+        backup="${backup_dir}/$(basename "$file").${ts}"
         [[ -f "$backup" ]] || cp -a "$file" "$backup"
     }
 
+    # Copies an earlier version left next to the originals move there too.
+    local stray
+    for stray in /etc/apt/sources.list.proxmenux-backup.* /etc/apt/sources.list.d/*.proxmenux-backup.*; do
+        [[ -f "$stray" ]] || continue
+        mkdir -p "$backup_dir"
+        mv -f "$stray" "${backup_dir}/$(basename "${stray/.proxmenux-backup./.}")"
+    done
+
     # ── Phase 1 — comment intra-file duplicates in sources.list by URL+Suite ──
     if [ -s "$sources_file" ]; then
         local temp_file
@@ -207,7 +218,7 @@ cleanup_duplicate_repos_pve9() {
                 esc_uri=$(printf '%s' "$uri" | sed 's/[][\.^$*/]/\\&/g')
                 esc_suite=$(printf '%s' "$suite" | sed 's/[][\.^$*/]/\\&/g')
                 esc_comp=$(printf '%s' "$first_comp" | sed 's/[][\.^$*/]/\\&/g')
-                pmx_edit_file "$target_file" -E "/^deb[[:space:]]+${esc_uri}[[:space:]]+${esc_suite}[[:space:]]+.*(^| )${esc_comp}( |$)/s/^/# /"
+                pmx_edit_file "$target_file" -E "/^deb[[:space:]]+${esc_uri}[[:space:]]+${esc_suite}[[:space:]](.*[[:space:]])?${esc_comp}([[:space:]]|$)/s/^/# /"
                 cleaned_count=$((cleaned_count + 1))
             fi
         }