diff --git a/misc/build.func b/misc/build.func
index 1b2a957faa..93208beef0 100644
--- a/misc/build.func
+++ b/misc/build.func
@@ -2954,15 +2954,14 @@ fix_gpu_gids() {
 
   # For privileged containers: also fix permissions inside container
   if [[ "$CT_TYPE" == "0" ]]; then
-    pct exec "$CTID" -- bash -c "
+    pct exec "$CTID" -- sh -c "
       if [ -d /dev/dri ]; then
         for dev in /dev/dri/*; do
           if [ -e \"\$dev\" ]; then
-            if [[ \"\$dev\" =~ renderD ]]; then
-              chgrp ${render_gid} \"\$dev\" 2>/dev/null || true
-            else
-              chgrp ${video_gid} \"\$dev\" 2>/dev/null || true
-            fi
+            case \"\$dev\" in
+              *renderD*) chgrp ${render_gid} \"\$dev\" 2>/dev/null || true ;;
+              *)         chgrp ${video_gid} \"\$dev\" 2>/dev/null || true ;;
+            esac
             chmod 660 \"\$dev\" 2>/dev/null || true
           fi
         done
diff --git a/misc/tools.func b/misc/tools.func
index 63aad95b48..5895141b59 100644
--- a/misc/tools.func
+++ b/misc/tools.func
@@ -192,6 +192,8 @@ install_packages_with_retry() {
     if [[ $retry -le $max_retries ]]; then
       msg_warn "Package installation failed, retrying ($retry/$max_retries)..."
       sleep 2
+      # Fix any interrupted dpkg operations before retry
+      $STD dpkg --configure -a 2>/dev/null || true
       $STD apt update 2>/dev/null || true
     fi
   done
@@ -217,6 +219,8 @@ upgrade_packages_with_retry() {
     if [[ $retry -le $max_retries ]]; then
       msg_warn "Package upgrade failed, retrying ($retry/$max_retries)..."
       sleep 2
+      # Fix any interrupted dpkg operations before retry
+      $STD dpkg --configure -a 2>/dev/null || true
       $STD apt update 2>/dev/null || true
     fi
   done
@@ -1182,6 +1186,12 @@ cleanup_orphaned_sources() {
 # This should be called at the start of any setup function
 # ------------------------------------------------------------------------------
 ensure_apt_working() {
+  # Fix interrupted dpkg operations first
+  # This can happen if a previous installation was interrupted (e.g., by script error)
+  if [[ -f /var/lib/dpkg/lock-frontend ]] || dpkg --audit 2>&1 | grep -q "interrupted"; then
+    $STD dpkg --configure -a 2>/dev/null || true
+  fi
+
   # Clean up orphaned sources first
   cleanup_orphaned_sources