Getting ‘Permission denied’ error when trying to add product image to database using Admin panel

Hello.
I am working on an e-commerce project. Using the Admin panel, I tried to add a picture with product data in the database, but it failed and errors were displayed.

**
THIS SHOWED AS AN ERROR AFTER ATTEMPTING TO ADD A PRODUCT WITH A PICTURE**

Warning: move_uploaded_file(product_images/dress.jpeg): failed to open stream: Permission denied in /opt/lampp/htdocs/project/admin_area/includes/insert_product.php on line 115

Warning: move_uploaded_file(): Unable to move ‘/opt/lampp/temp/php48ULD8’ to ‘product_images/dress.jpeg’ in /opt/lampp/htdocs/project/admin_area/includes/insert_product.php on line 115

And this is the code where the error is showing

    <div class="form_box">

     <form action="" method="post" enctype="multipart/form-data">
       
       <table align="center" width="100%">
         
         <tr>
           <td colspan="7">
           <h2>Add Product</h2>
           <div class="border bottom"></div><! --/. border bottom -->
           </td>
         </tr>
         
         <tr>
           <td><b>Product Title:</b></td>
           <td><input type="text" name="product_title" size="60" required/></td>
         </tr>
         
         <tr>
           <td><b>Product Category:</b></td>
           <td>
            <select name="product_cat">
              <option>Select a Category</option>
              
              <?php 
              $get_cats ="select * from categories";
        
        $run_cats = mysqli_query($con, $get_cats);
        
        while($row_cats=mysqli_fetch_array($run_cats)){
            $cat_id = $row_cats['cat_id'];
            
            $cat_title = $row_cats['cat_title'];
            
            echo "<option value='$cat_id'>$cat_title</option>";
        }
              ?>
            </select>
           </td>
           
         </tr>
         
         <tr>
           <td><b>Product Brand:</b></td>
           <td>
            <select name="product_brand">
              <option>Select a Brand</option>
            <?php
              $get_brands = "select * from brands";
        
        $run_brands = mysqli_query($con, $get_brands);
        
        while($row_brands = mysqli_fetch_array($run_brands)){
             $brand_id = $row_brands['brand_id'];
             
             $brand_title = $row_brands['brand_title'];
             
             echo "<option value='$brand_id'>$brand_title</option>";
        }
        
        ?>
            </select>
           </td>
           
         </tr>
        
        <tr>
          <td><b>Product Image: </b></td>
          <td><input type="file" name="product_image" /></td>
        </tr>
        
        <tr>
          <td><b>Product Price: </b></td>
          <td><input type="text" name="product_price" required/></td>
        </tr>
        
        <tr>
           <td valign="top"><b>Product Description:</b></td>
           <td><textarea name="product_desc"  rows="10"></textarea></td>
        </tr>
        
        
        <tr>
          <td><b>Product Keywords: </b></td>
          <td><input type="text" name="product_keywords" required/></td>
        </tr>
        
        <tr>
           <td></td>
           <td colspan="7"><input type="submit" name="insert_post" value="Add Product"/></td>
        </tr>
       </table>
       
     </form>
     
  </div><!-- /.form_box -->

<?php 

if(isset($_POST['insert_post'])){
   $product_title = $_POST['product_title'];
   $product_cat = $_POST['product_cat'];
   $product_brand = $_POST['product_brand'];
   $product_price = $_POST['product_price'];
   $product_desc = trim(mysqli_real_escape_string($con,$_POST['product_desc']));
   $product_keywords = $_POST['product_keywords']; 
   
   
   // Getting the image from the field
   $product_image  = $_FILES['product_image']['name'];
   $product_image_tmp = $_FILES['product_image']['tmp_name'];
   
   move_uploaded_file($product_image_tmp,"product_images/$product_image");
   
   $insert_product = " insert into products (product_cat,product_brand,product_title,product_price,product_desc,product_image,product_keywords) 
   values ('$product_cat','$product_brand','$product_title','$product_price','$product_desc','$product_image','$product_keywords') ";

   $insert_pro = mysqli_query($con, $insert_product);
   
   if($insert_pro){
    echo "<script>alert('Product Has Been inserted successfully!')</script>";
    
    //echo "<script>window.open('index.php?insert_product','_self')</script>";
   }
   
   }
?>

I tried to add various permissions, but nothing could be solved.