diff --git a/EnvelopeGenerator.ReceiverUI/Pages/EnvelopeViewer.razor b/EnvelopeGenerator.ReceiverUI/Pages/EnvelopeViewer.razor
index 82e52514..dcdf9971 100644
--- a/EnvelopeGenerator.ReceiverUI/Pages/EnvelopeViewer.razor
+++ b/EnvelopeGenerator.ReceiverUI/Pages/EnvelopeViewer.razor
@@ -223,7 +223,8 @@
                     _currentPage = await JSRuntime.InvokeAsync<int>("pdfViewer.getCurrentPage");
                     await InvokeAsync(StateHasChanged);
                     
-                    // Render thumbnails
+                    // Wait for DOM to be ready, then render thumbnails
+                    await Task.Delay(100);
                     await RenderThumbnailsAsync();
                 }
             } catch (Exception ex) {
@@ -304,11 +305,18 @@
 
     async Task RenderThumbnailsAsync() {
         try {
+            // Sequential rendering to avoid overwhelming the browser
             for (int i = 1; i <= _totalPages; i++) {
                 await JSRuntime.InvokeVoidAsync("pdfViewer.renderThumbnail", i, $"thumb-canvas-{i}");
+                
+                // Small delay between renders to keep UI responsive
+                if (i < _totalPages) {
+                    await Task.Delay(50);
+                }
             }
-        } catch (Exception) {
+        } catch (Exception ex) {
             // Thumbnail rendering is not critical
+            System.Diagnostics.Debug.WriteLine($"Thumbnail rendering error: {ex.Message}");
         }
     }
 
diff --git a/EnvelopeGenerator.ReceiverUI/wwwroot/js/pdf-viewer.js b/EnvelopeGenerator.ReceiverUI/wwwroot/js/pdf-viewer.js
index 0f66a55d..91c8f650 100644
--- a/EnvelopeGenerator.ReceiverUI/wwwroot/js/pdf-viewer.js
+++ b/EnvelopeGenerator.ReceiverUI/wwwroot/js/pdf-viewer.js
@@ -234,11 +234,25 @@ window.pdfViewer = {
     },
 
     async renderThumbnail(pageNum, canvasId) {
-        if (!this.pdfDoc) return;
+        if (!this.pdfDoc) {
+            console.error('PDF document not loaded for thumbnail:', pageNum);
+            return;
+        }
 
         try {
-            const canvas = document.getElementById(canvasId);
-            if (!canvas) return;
+            // Wait for canvas to be in DOM
+            let canvas = document.getElementById(canvasId);
+            let retries = 0;
+            while (!canvas && retries < 10) {
+                await new Promise(resolve => setTimeout(resolve, 100));
+                canvas = document.getElementById(canvasId);
+                retries++;
+            }
+
+            if (!canvas) {
+                console.error('Canvas not found after retries:', canvasId);
+                return;
+            }
 
             const page = await this.pdfDoc.getPage(pageNum);
             const viewport = page.getViewport({ scale: 0.2 });
@@ -254,7 +268,7 @@ window.pdfViewer = {
 
             await page.render(renderContext).promise;
         } catch (error) {
-            // Thumbnail rendering errors are non-critical
+            console.error('Error rendering thumbnail', pageNum, ':', error);
         }
     },