diff --git a/tools/port/check-all b/tools/port/check-all
index 007bb095..bb4af696 100755
--- a/tools/port/check-all
+++ b/tools/port/check-all
@@ -54,7 +54,13 @@ step() { # name, expectation, command...
 if ! DISPLAY="$DISPLAY" timeout 10 xdpyinfo >/dev/null 2>&1; then
   echo "🔴 no X display on $DISPLAY -- every Godot step below would fail for that one reason."
   echo "   Xvfb does not survive a container restart and leaves its socket behind. Start it with:"
-  echo "     rm -f /tmp/.X11-unix/X\${DISPLAY#:} ; Xvfb $DISPLAY -screen 0 1280x720x24 -nolisten tcp &"
+  echo "     rm -f /tmp/.X11-unix/X\${DISPLAY#:} /tmp/.X\${DISPLAY#:}-lock"
+  echo "     Xvfb $DISPLAY -screen 0 1280x720x24 -nolisten tcp &"
+  echo "   🔴 THE LOCK FILE IS NOT OPTIONAL and this recipe omitted it until"
+  echo "      2026-09-03. Removing only the socket leaves /tmp/.X<n>-lock behind,"
+  echo "      Xvfb exits 1 immediately, and the next command still reports no"
+  echo "      display -- which reads as the restart having failed for some deeper"
+  echo "      reason. Cost three occurrences before anyone read Xvfb's own stderr."
   exit 3
 fi