diff --git a/src/main/webapp/app/lecture/pdf-preview/pdf-preview-thumbnail-grid/pdf-preview-thumbnail-grid.component.ts b/src/main/webapp/app/lecture/pdf-preview/pdf-preview-thumbnail-grid/pdf-preview-thumbnail-grid.component.ts
index 50bd4e11433d..e20bd50d9f08 100644
--- a/src/main/webapp/app/lecture/pdf-preview/pdf-preview-thumbnail-grid/pdf-preview-thumbnail-grid.component.ts
+++ b/src/main/webapp/app/lecture/pdf-preview/pdf-preview-thumbnail-grid/pdf-preview-thumbnail-grid.component.ts
@@ -1,4 +1,4 @@
-import { Component, ElementRef, effect, inject, input, output, signal, viewChild } from '@angular/core';
+import { Component, ElementRef, OnChanges, SimpleChanges, effect, inject, input, output, signal, viewChild } from '@angular/core';
 import * as PDFJS from 'pdfjs-dist';
 import 'pdfjs-dist/build/pdf.worker';
 import { ArtemisSharedModule } from 'app/shared/shared.module';
@@ -14,7 +14,7 @@ import { clone } from 'lodash-es';
     standalone: true,
     imports: [ArtemisSharedModule, PdfPreviewEnlargedCanvasComponent],
 })
-export class PdfPreviewThumbnailGridComponent {
+export class PdfPreviewThumbnailGridComponent implements OnChanges {
     pdfContainer = viewChild.required<ElementRef<HTMLDivElement>>('pdfContainer');
 
     readonly DEFAULT_SLIDE_WIDTH = 250;
@@ -42,10 +42,15 @@ export class PdfPreviewThumbnailGridComponent {
     // Injected services
     private readonly alertService = inject(AlertService);
 
+    ngOnChanges(changes: SimpleChanges): void {
+        if (changes['hiddenPages']) {
+            this.newHiddenPages.set(clone(this.hiddenPages()!));
+        }
+    }
+
     constructor() {
         effect(
             () => {
-                this.newHiddenPages.set(clone(this.hiddenPages()!));
                 this.loadOrAppendPdf(this.currentPdfUrl()!, this.appendFile());
             },
             { allowSignalWrites: true },
diff --git a/src/main/webapp/app/lecture/pdf-preview/pdf-preview.component.html b/src/main/webapp/app/lecture/pdf-preview/pdf-preview.component.html
index 5ed0f41459f8..b4b2ec510e1a 100644
--- a/src/main/webapp/app/lecture/pdf-preview/pdf-preview.component.html
+++ b/src/main/webapp/app/lecture/pdf-preview/pdf-preview.component.html
@@ -48,7 +48,7 @@ <h4>
                 (isPdfLoading)="isPdfLoading.set($event)"
                 (selectedPagesOutput)="selectedPages.set($event)"
                 (totalPagesOutput)="totalPages.set($event)"
-                (newHiddenPagesOutput)="newHiddenPages.set($event)"
+                (newHiddenPagesOutput)="hiddenPages.set($event)"
             />
         } @else {
             <div class="empty-pdf-container"></div>
diff --git a/src/main/webapp/app/lecture/pdf-preview/pdf-preview.component.ts b/src/main/webapp/app/lecture/pdf-preview/pdf-preview.component.ts
index b113c8dea87b..cb41ce2f1f8a 100644
--- a/src/main/webapp/app/lecture/pdf-preview/pdf-preview.component.ts
+++ b/src/main/webapp/app/lecture/pdf-preview/pdf-preview.component.ts
@@ -114,7 +114,8 @@ export class PdfPreviewComponent implements OnInit, OnDestroy {
      * Triggers the file input to select files.
      */
     triggerFileInput(): void {
-        this.fileInput().nativeElement.click();
+        //this.fileInput().nativeElement.click();
+        console.log(this.hiddenPages());
     }
 
     /**
@@ -228,9 +229,9 @@ export class PdfPreviewComponent implements OnInit, OnDestroy {
             const pagesToDelete = Array.from(this.selectedPages()!)
                 .map((page) => page - 1)
                 .sort((a, b) => b - a);
-            pagesToDelete.forEach((pageIndex) => {
-                pdfDoc.removePage(pageIndex);
-            });
+
+            this.updateHiddenPages(pagesToDelete);
+            pagesToDelete.forEach((pageIndex) => pdfDoc.removePage(pageIndex));
 
             this.isFileChanged.set(true);
             const pdfBytes = await pdfDoc.save();
@@ -248,6 +249,27 @@ export class PdfPreviewComponent implements OnInit, OnDestroy {
         }
     }
 
+    /**
+     * Updates hidden pages after selected pages are deleted.
+     * @param pagesToDelete - Array of pages to be deleted (0-indexed).
+     */
+    private updateHiddenPages(pagesToDelete: number[]) {
+        const updatedHiddenPages = new Set<number>();
+        this.hiddenPages().forEach((hiddenPage) => {
+            // Adjust hiddenPage based on the deleted pages
+            const adjustedPage = pagesToDelete.reduce((acc, pageIndex) => {
+                if (acc === pageIndex + 1) {
+                    return;
+                }
+                return pageIndex < acc - 1 ? acc - 1 : acc;
+            }, hiddenPage);
+            if (adjustedPage !== -1) {
+                updatedHiddenPages.add(adjustedPage!);
+            }
+        });
+        this.hiddenPages.set(updatedHiddenPages);
+    }
+
     /**
      * Adds a selected PDF file at the end of the current PDF document.
      * @param event - The event containing the file input.