diff --git a/docs/webserver.md b/docs/webserver.md
index 355bac41..d1d3bac5 100644
--- a/docs/webserver.md
+++ b/docs/webserver.md
@@ -153,7 +153,7 @@ Click **File Manager** to access file management features.
 
 1. Click the **+ Add** button in the top-right corner
 2. Select **New Folder** from the dropdown menu
-3. Enter a folder name (letters, numbers, underscores, and hyphens only)
+3. Enter a folder name (must not contain characters \" * : < > ? / \\ | and must not be . or ..)
 4. Click **Create Folder**
 
 This is useful for organizing your ebooks by genre, author, or series.
diff --git a/src/network/html/FilesPage.html b/src/network/html/FilesPage.html
index bfdbe3cc..95993b8e 100644
--- a/src/network/html/FilesPage.html
+++ b/src/network/html/FilesPage.html
@@ -1146,10 +1146,10 @@ function retryAllFailedUploads() {
       return;
     }
 
-    // Validate folder name (no special characters except underscore and hyphen)
-    const validName = /^[a-zA-Z0-9_\-]+$/.test(folderName);
+    // Validate folder name
+    const validName = /^(?!\.{1,2}$)[^"*:<>?\/\\|]+$/.test(folderName);
     if (!validName) {
-      alert('Folder name can only contain letters, numbers, underscores, and hyphens.');
+      alert('Folder name cannot contain \" * : < > ? / \\ | and must not be . or ..');
       return;
     }