diff --git a/.github/workflows/test-build.yml b/.github/workflows/test-build.yml
index 03d7994..b1a0e2f 100644
--- a/.github/workflows/test-build.yml
+++ b/.github/workflows/test-build.yml
@@ -99,6 +99,7 @@ jobs:
 
     - name: Archive VM test results
       uses: actions/upload-artifact@v4
+      if: always()
       with:
         name: vm-results-${{matrix.host_release}}-${{matrix.release}}-${{matrix.debootstrap}}
         if-no-files-found: error
diff --git a/tests/README.md b/tests/README.md
new file mode 100644
index 0000000..2417bb5
--- /dev/null
+++ b/tests/README.md
@@ -0,0 +1,23 @@
+# Tests
+
+The `tests` directory provides scripts and configuration files which are used within [grml-debootstrap's GitHub actions](https://github.com/grml/grml-debootstrap/actions).
+
+> [!CAUTION]
+> executing the scripts is potentially dangerous and may destroy the host system and/or any data. Run the tests only on throw-away systems and at your own risk.
+
+The scripts are **not** designed to be executed manually, though it's possible to run them inside a local Debian throw-away VM.
+
+> [!NOTE]
+> make sure to have at least 8GB disk space and 2GB memory available on your VM.
+
+Execute the following steps to build a Debian VM image (`qemu.img`) and run the tests against it:
+
+```
+sudo apt install git docker.io
+git clone https://github.com/grml/grml-debootstrap
+cd grml-debootstrap
+sudo ./tests/docker-build-deb.sh --autobuild 01
+sudo ./tests/build-vm-and-test.sh setup
+sudo ./tests/build-vm-and-test.sh run
+sudo ./tests/build-vm-and-test.sh test
+```
diff --git a/tests/build-vm-and-test.sh b/tests/build-vm-and-test.sh
index 53076ac..c88c6c5 100755
--- a/tests/build-vm-and-test.sh
+++ b/tests/build-vm-and-test.sh
@@ -32,9 +32,11 @@ if [ ! -d ./tests ]; then
 fi
 
 if [ "$1" == "setup" ]; then
-  [ -x ./tests/goss ] || curl -fsSL https://goss.rocks/install | GOSS_DST="$(pwd)/tests" sh
   sudo apt-get update
-  sudo apt-get -qq -y install qemu-system-x86 kpartx python3-pexpect python3-serial
+  sudo apt-get -qq -y install curl qemu-system-x86 kpartx python3-pexpect python3-serial
+  # vncsnapshot might not be available, though we don't want to abort execution then
+  sudo apt-get -qq -y install vncsnapshot || true
+  [ -x ./tests/goss ] || curl -fsSL https://goss.rocks/install | GOSS_DST="$(pwd)/tests" sh
   # TODO: docker.io
   exit 0
 fi
diff --git a/tests/serial-console-connection b/tests/serial-console-connection
index b44299a..30e6bb8 100755
--- a/tests/serial-console-connection
+++ b/tests/serial-console-connection
@@ -1,6 +1,9 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 import argparse
 import serial
+import os
+import shutil
+import subprocess
 import sys
 import time
 from pexpect import fdpexpect
@@ -15,7 +18,7 @@ parser.add_argument(
     help="serial console device to connect " + "to (e.g. /dev/pts/X)",
 )
 parser.add_argument(
-    "--hostname", default="buster", help="hostname of the system for login process"
+    "--hostname", default="bookworm", help="hostname of the system for login process"
 )
 parser.add_argument("--user", default="root", help="user name to use for login")
 parser.add_argument("--password", default="grml", help="password for login")
@@ -25,6 +28,11 @@ parser.add_argument(
     type=int,
     help="Maximum time for finding the login prompt, in seconds",
 )
+parser.add_argument(
+    "--screenshot",
+    default="screenshot.jpg",
+    help="file name for screenshot captured via VNC on error",
+)
 parser.add_argument(
     "--tries",
     default="12",
@@ -74,6 +82,21 @@ def login(ser, hostname, user, password, timeout=5):
     child.expect("%s@%s" % (user, hostname), timeout=timeout)
 
 
+def capture_vnc_screenshot(screenshot_file):
+    if not shutil.which("vncsnapshot"):
+        print("WARN: vncsnapshot not available, skipping vnc snapshot capturing.")
+        return
+
+    print("Trying to capture screenshot via vncsnapshot to", screenshot_file)
+
+    proc = subprocess.Popen(["vncsnapshot", "localhost", screenshot_file])
+    proc.wait()
+    if proc.returncode != 0:
+        print("WARN: failed to capture vnc snapshot :(")
+    else:
+        print("Screenshot file '%s' available" % os.path.abspath(screenshot_file))
+
+
 def main():
     args = parser.parse_args()
     hostname = args.hostname
@@ -81,6 +104,7 @@ def main():
     port = args.port
     user = args.user
     commands = args.command
+    screenshot_file = args.screenshot
 
     ser = serial.Serial(port, 115200)
     ser.flushInput()
@@ -116,6 +140,7 @@ def main():
             # after poweroff, the serial device will probably vanish. do not attempt reading from it anymore.
 
     if not success:
+        capture_vnc_screenshot(screenshot_file)
         sys.exit(1)
 
 
diff --git a/tests/test-vm.sh b/tests/test-vm.sh
index 85e46c5..969709d 100755
--- a/tests/test-vm.sh
+++ b/tests/test-vm.sh
@@ -114,12 +114,14 @@ if [ "$success" = "0" ] ; then
   exit 1
 fi
 
+RC=0
 "$TEST_PWD"/tests/serial-console-connection \
   --tries 180 \
+  --screenshot "$TEST_PWD/tests/screenshot.jpg" \
   --port "$serial_port" \
   --hostname "$VM_HOSTNAME" \
   --poweroff \
-  "mount -t 9p -o trans=virtio,version=9p2000.L,rw $MOUNT_TAG /mnt && cd /mnt && ./testrunner"
+  "mount -t 9p -o trans=virtio,version=9p2000.L,rw $MOUNT_TAG /mnt && cd /mnt && ./testrunner" || RC=$?
 
 if [ ! -d results ] || [ ! -f ./results/goss.tap ] || [ ! -f ./results/goss.exitcode ]; then
   echo "Running tests inside VM failed for unknown reason" >&2
@@ -133,7 +135,14 @@ fi
 
 echo "Finished serial console connection [timeout=${timeout}]."
 
-mv results/* "$TESTS_RESULTSDIR/"
+# in case of errors we might have captured a screenshot via VNC
+if [ -r "${TEST_PWD}"/tests/screenshot.jpg ] ; then
+  cp "${TEST_PWD}"/tests/screenshot.jpg "${TESTS_RESULTSDIR}"
+fi
+
+if [ -d results ] ; then
+  mv results/* "$TESTS_RESULTSDIR/"
+fi
 
 bailout $RC