diff --git a/src/main/java/com/maradona/backend/DefaultValueLoader.java b/src/main/java/com/maradona/backend/DefaultValueLoader.java
index 09df26e..f66470c 100644
--- a/src/main/java/com/maradona/backend/DefaultValueLoader.java
+++ b/src/main/java/com/maradona/backend/DefaultValueLoader.java
@@ -35,11 +35,9 @@ public class DefaultValueLoader implements CommandLineRunner {
   @Override
   public void run(String... args) {
 
-    // Clear all tables
-    employeeRepository.deleteAll();
-    secondarySkillRepository.deleteAll();
-    primarySkillRepository.deleteAll();
-    formOfAddressRepository.deleteAll();
+    if (employeeRepository.count() > 0) {
+      return;
+    }
 
     // Create form of addresses
     FormOfAddress formOfAddress1 = new FormOfAddress();
@@ -48,9 +46,6 @@ public class DefaultValueLoader implements CommandLineRunner {
     FormOfAddress formOfAddress2 = new FormOfAddress();
     formOfAddress2.setDescription("Frau");
 
-    FormOfAddress formOfAddress3 = new FormOfAddress();
-    formOfAddress3.setDescription("Einkaufstüte");
-
     formOfAddress1 = formOfAddressRepository.save(formOfAddress1);
     formOfAddress2 = formOfAddressRepository.save(formOfAddress2);
 
diff --git a/src/main/java/com/maradona/backend/controllers/page/ErrorPage.java b/src/main/java/com/maradona/backend/controllers/page/ErrorPage.java
new file mode 100644
index 0000000..b43024d
--- /dev/null
+++ b/src/main/java/com/maradona/backend/controllers/page/ErrorPage.java
@@ -0,0 +1,58 @@
+package com.maradona.backend.controllers.page;
+
+import org.springframework.stereotype.Controller;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RequestMapping;
+
+/**
+ * Controller for routing to the error pages.
+ * 
+ * List of endpoints:
+ * - GET /error/400
+ * - GET /error/404
+ * - GET /error/500
+ */
+@Controller
+@RequestMapping("/error")
+public class ErrorPage {
+  /**
+   * Error page for 400 Bad Request.
+   * 
+   * This page is displayed when the request is malformed and the server cannot
+   * process it.
+   * 
+   * @return The 400 error page template.
+   */
+  @GetMapping("/400")
+  public String error400() {
+    return "pages/error/400";
+  }
+
+  /**
+   * Error page for 404 Not Found.
+   * 
+   * This page is displayed when the requested resource could not be found on the
+   * server. This can be due to a wrong URL or a deleted resource. The user should
+   * be informed that the resource is not available.
+   * 
+   * @return The 404 error page template.
+   */
+  @GetMapping("/404")
+  public String error404() {
+    return "pages/error/404";
+  }
+
+  /**
+   * Error page for 500 Internal Server Error.
+   * 
+   * This page is displayed when the server encountered an unexpected condition
+   * that prevented it from fulfilling the request. The user should be informed
+   * that the server is experiencing problems and the request cannot be processed.
+   * 
+   * @return The 500 error page template.
+   */
+  @GetMapping("/500")
+  public String error500() {
+    return "pages/error/500";
+  }
+}
diff --git a/src/main/java/com/maradona/backend/controllers/page/Page.java b/src/main/java/com/maradona/backend/controllers/page/Page.java
index d252e55..18a74ac 100644
--- a/src/main/java/com/maradona/backend/controllers/page/Page.java
+++ b/src/main/java/com/maradona/backend/controllers/page/Page.java
@@ -4,24 +4,53 @@ import org.springframework.stereotype.Controller;
 import org.springframework.ui.Model;
 import org.springframework.web.bind.annotation.GetMapping;
 
+/**
+ * Controller for routing to the core pages.
+ * 
+ * List of endpoints:
+ * - GET /
+ * - GET /impressum
+ * - GET /datenschutz
+ * - GET /notes
+ */
 @Controller
 public class Page {
-
+  /**
+   * Returns the home page.
+   * 
+   * @param model The model with the data to be displayed.
+   * @return The home page template.
+   */
   @GetMapping({ "/", "" })
   public String home(Model model) {
     return "pages/core/home";
   }
 
+  /**
+   * Returns the impressum page.
+   * 
+   * @return The impressum page template.
+   */
   @GetMapping("/impressum")
   public String impressum() {
     return "pages/core/impressum";
   }
 
+  /**
+   * Returns the datenschutz page.
+   * 
+   * @return The datenschutz page template.
+   */
   @GetMapping("/datenschutz")
   public String datenschutz() {
     return "pages/core/datenschutz";
   }
 
+  /**
+   * Returns the notes page.
+   * 
+   * @return The notes page template.
+   */
   @GetMapping("/notes")
   public String notes() {
     return "pages/core/notes";
diff --git a/src/main/java/com/maradona/backend/controllers/page/SkillsPage.java b/src/main/java/com/maradona/backend/controllers/page/SkillsPage.java
index 3b298d3..207c98b 100644
--- a/src/main/java/com/maradona/backend/controllers/page/SkillsPage.java
+++ b/src/main/java/com/maradona/backend/controllers/page/SkillsPage.java
@@ -52,7 +52,11 @@ public class SkillsPage {
    */
   @GetMapping({ "/", "" })
   public String profile(Model model) {
-    model.addAttribute("employee", employeeDetails.getEmployeeByEid(user).orElse(null));
+    var employee = employeeDetails.getEmployeeByEid(user).orElse(null);
+    if (employee == null) {
+      return "/404";
+    }
+    model.addAttribute("employee", employee);
     model.addAttribute("skills", skillService.getUserSkills(user));
     return "/pages/skills/overview";
   }
diff --git a/src/main/java/com/maradona/backend/entities/Employee.java b/src/main/java/com/maradona/backend/entities/Employee.java
index 9c85ae0..5cf719e 100644
--- a/src/main/java/com/maradona/backend/entities/Employee.java
+++ b/src/main/java/com/maradona/backend/entities/Employee.java
@@ -24,7 +24,7 @@ public class Employee {
     private String lastName;
 
     @ManyToOne
-    @JoinColumn(name = "FID", referencedColumnName = "fid")
+    @JoinColumn(name = "fid")
     private FormOfAddress formOfAddress;
 
     private LocalTime dStart;