diff --git a/.drone.yml b/.drone.yml
index 940a6dc..d8c9dcb 100644
--- a/.drone.yml
+++ b/.drone.yml
@@ -1,12 +1,19 @@
 kind: pipeline
 type: docker
 name: default
-
 steps:
-  - name: test
+  - name: build
     image: maven:3.8-openjdk-18-slim
     commands:
       - mvn clean install -DskipTests=true -Dmaven.javadoc.skip=true -B -V
+    when:
+      branch:
+        include:
+          - master
+          - feature/*
+  - name: test
+    image: maven:3.8-openjdk-18-slim
+    commands:
       - mvn test -B
     when:
       branch:
@@ -25,4 +32,40 @@ steps:
         - master
       event:
         exclude:
-        - pull_request
+          - pull_request
+  - name: build_docker_image
+    image: plugins/docker
+    settings:
+      registry: gittr.ch
+      username: manuel
+      password:
+        from_secret: docker-token
+      repo: gittr.ch/java/labyrinth
+      tags:
+        - latest
+      dockerfile: docker/Dockerfile
+    when:
+      branch:
+        - master
+      event:
+        exclude:
+          - pull_request
+          - tag
+  - name: build_docker_image_release
+    image: plugins/docker
+    settings:
+      registry: gittr.ch
+      username: manuel
+      password:
+        from_secret: docker-token
+      repo: gittr.ch/java/labyrinth
+      tags:
+        - latest
+        - ${DRONE_TAG}
+      dockerfile: docker/Dockerfile
+    when:
+      branch:
+        - master
+      event:
+        include:
+          - tag
diff --git a/docker/Dockerfile b/docker/Dockerfile
index abccd12..8c0219c 100644
--- a/docker/Dockerfile
+++ b/docker/Dockerfile
@@ -1,4 +1,4 @@
-FROM openjdk:11
+FROM openjdk:17-slim
 
 COPY target/labyrinth-server-*.jar /app/app.jar
 
diff --git a/pom.xml b/pom.xml
index 3518f8b..ecd2143 100644
--- a/pom.xml
+++ b/pom.xml
@@ -18,6 +18,8 @@
 		<logback.version>1.4.6</logback.version>
 		<lombok.version>1.18.26</lombok.version>
 		<slf4j.version>2.0.5</slf4j.version>
+		<java.source.version>17</java.source.version>
+		<java.target.version>17</java.target.version>
 	</properties>
 
 	<dependencies>
diff --git a/src/main/java/ch/fritteli/labyrinth/server/LabyrinthServer.java b/src/main/java/ch/fritteli/labyrinth/server/LabyrinthServer.java
index 689d9bc..aab20f6 100644
--- a/src/main/java/ch/fritteli/labyrinth/server/LabyrinthServer.java
+++ b/src/main/java/ch/fritteli/labyrinth/server/LabyrinthServer.java
@@ -105,15 +105,15 @@ public class LabyrinthServer {
                     exchange.sendResponseHeaders(302, -1);
                     return;
                 }
-                final Labyrinth labyrinth = new Labyrinth(width, height, id);
                 final byte[] render;
                 try {
+                    final Labyrinth labyrinth = new Labyrinth(width, height, id);
                     render = output.render(labyrinth);
                 } catch (Exception e) {
                     responseHeaders.add("Content-type", "text/plain; charset=UTF-8");
                     exchange.sendResponseHeaders(500, 0);
                     final OutputStream responseBody = exchange.getResponseBody();
-                    responseBody.write(("Error: " + e).getBytes(StandardCharsets.UTF_8));
+                    responseBody.write(("Error: " + e.getMessage()).getBytes(StandardCharsets.UTF_8));
                     responseBody.flush();
                     return;
                 }