diff --git a/data/duke.txt b/data/duke.txt
index 6eb77ab5b9..665a8492e1 100644
Binary files a/data/duke.txt and b/data/duke.txt differ
diff --git a/src/main/java/monday/MainWindow.java b/src/main/java/monday/MainWindow.java
index 16ab14d2ca..269da99bff 100644
--- a/src/main/java/monday/MainWindow.java
+++ b/src/main/java/monday/MainWindow.java
@@ -10,7 +10,6 @@
 import javafx.scene.layout.VBox;
 import javafx.stage.Stage;
 import javafx.util.Duration;
-
 import monday.monday.ui.Ui;
 
 /**
@@ -31,6 +30,9 @@ public class MainWindow extends AnchorPane {
     private Image userImage = new Image(this.getClass().getResourceAsStream("/images/bai.png"));
     private Image mondayImage = new Image(this.getClass().getResourceAsStream("/images/fa.png"));
 
+    /**
+     * Start the programme and greets the user on start of program.
+     */
     @FXML
     public void initialize() {
         dialogContainer.getChildren().add(DialogBox.getDukeDialog(Ui.greet(), mondayImage));
diff --git a/src/main/java/monday/Monday.java b/src/main/java/monday/Monday.java
index 75e88bc7fe..15fa837d04 100644
--- a/src/main/java/monday/Monday.java
+++ b/src/main/java/monday/Monday.java
@@ -38,12 +38,6 @@ private void startMonday() {
                 System.out.println(p.parseCommands(userInput));
             } catch (MondayException e) {
                 Ui.printErrorMessage("", e);
-            } catch (NumberFormatException e) {
-                Ui.printErrorMessage("Mark/UnMark number error: ", e);
-            } catch (IllegalArgumentException e) {
-                Ui.printErrorMessage("Argument Error: ", e);
-            } catch (IndexOutOfBoundsException e) {
-                Ui.printErrorMessage("Index out of Bound Error: ", e);
             }
             Ui.printSeparator();
         }
diff --git a/src/main/java/monday/monday/parser/Parser.java b/src/main/java/monday/monday/parser/Parser.java
index 031ff5a2a8..02575372bf 100644
--- a/src/main/java/monday/monday/parser/Parser.java
+++ b/src/main/java/monday/monday/parser/Parser.java
@@ -161,7 +161,7 @@ private String deadLineCommand(String content) throws MondayException {
 
             return taskList.addToList(new Deadline(description.trim(), date.trim()));
         } catch (ArrayIndexOutOfBoundsException e) {
-            throw new IllegalArgumentException("Invalid Format. "
+            throw new MondayException("Invalid Format. "
                     + "Usage: deadline (task) /by (time)");
         }
     }
@@ -190,7 +190,7 @@ private String eventCommand(String content) throws MondayException {
                     start.trim(),
                     end.trim()));
         } catch (ArrayIndexOutOfBoundsException e) {
-            throw new IllegalArgumentException("Invalid Format. "
+            throw new MondayException("Invalid Format. "
                     + "Usage: event (task) /from (start time) /to (end time)");
         }
     }
@@ -229,7 +229,7 @@ private String findCommand(String content) throws MondayException {
         String[] keywordDetails = content.split(" ");
 
         if (keywordDetails.length > 1) {
-            throw new IllegalArgumentException("Invalid Format. "
+            throw new MondayException("Invalid Format. "
                     + "Usage: find (keyword), there should only be one keyword.");
         }
 
diff --git a/src/main/java/monday/task/TaskList.java b/src/main/java/monday/task/TaskList.java
index c3418aa516..95fa5b4be4 100644
--- a/src/main/java/monday/task/TaskList.java
+++ b/src/main/java/monday/task/TaskList.java
@@ -3,6 +3,7 @@
 import java.io.IOException;
 import java.util.ArrayList;
 
+import monday.monday.exception.MondayException;
 import monday.monday.ui.Ui;
 import monday.storage.TaskArrayListStorage;
 
@@ -71,12 +72,12 @@ public String toString() {
      *
      * @param index The index of the task to be marked as done.
      * @return Message after marking the task as done.
-     * @throws IndexOutOfBoundsException If the index is out of range.
+     * @throws MondayException If the index is out of range.
      */
-    public String mark(int index) {
+    public String mark(int index) throws MondayException {
         assert !tasks.isEmpty() : "Your task list is empty, please add more elements.";
         if (index < 1 || index > tasks.size()) {
-            throw new IndexOutOfBoundsException("Task index is out of range. "
+            throw new MondayException("Task index is out of range. "
                     + "Check the number of tasks using the 'list' command.");
         }
         Task taskToEdit = tasks.get(index - 1);
@@ -90,12 +91,12 @@ public String mark(int index) {
      *
      * @param index The index of the task to be marked as not done.
      * @return Message after marking the task as not done.
-     * @throws IndexOutOfBoundsException If the index is out of range.
+     * @throws MondayException If the index is out of range.
      */
-    public String unMark(int index) {
+    public String unMark(int index) throws MondayException {
         assert !tasks.isEmpty() : "Your task list is empty, please add more elements.";
         if (index < 1 || index > tasks.size()) {
-            throw new IndexOutOfBoundsException("Task index is out of range. "
+            throw new MondayException("Task index is out of range. "
                     + "Check the number of tasks using the 'list' command.");
         }
         Task taskToEdit = tasks.get(index - 1);
@@ -109,12 +110,12 @@ public String unMark(int index) {
      *
      * @param index The index of the task to be deleted.
      * @return Message after deleting the task.
-     * @throws IndexOutOfBoundsException If the index is out of range.
+     * @throws MondayException If the index is out of range.
      */
-    public String delete(int index) {
+    public String delete(int index) throws MondayException {
         assert !tasks.isEmpty() : "Your task list is empty, please add more elements.";
         if (index < 1 || index > tasks.size()) {
-            throw new IndexOutOfBoundsException("Task index is out of range. "
+            throw new MondayException("Task index is out of range. "
                     + "Check the number of tasks using the 'list' command.");
         }
         Task taskToEdit = tasks.get(index - 1);