Import Demo Data fail

I am receiving this error when I clicked Import Demo Data button:

Failed to import pa_color Black
Failed to import pa_color Blue
Failed to import pa_color Green
Failed to import pa_size L
Failed to import pa_size M
Failed to import pa_size S
Failed to import pa_size XL
Media “750x250_oxy_1-750×250” already exists.
Media “750x250_default2_1” already exists.
Media “750x250_default2_2” already exists.
Media “750x250_default2_3” already exists.
Media “750x250_default4_1” already exists.
Media “750x250_default4_2” already exists.
Media “750x250_default4_3” already exists.
Media “1170_1” already exists.
Media “1170_2” already exists.
Media “1170_3” already exists.
Media “V6922-00X-001_1b-600×8001” already exists.
Media “V6922-00X-002_1b-600×8001” already exists.
Media “brand_ance_vintage_1[1]” already exists.
Page “Checkout” already exists.
Page “My Account” already exists.
Page “Mijireh Secure Checkout” already exists.
Page “Home” already exists.
Page “About Us” already exists.
Page “Terms & Conditions” already exists.
Page “Privacy Policy” already exists.
Page “Delivery Information” already exists.
Page “Returns” already exists.
Page “Long” already exists.
Page “Blog” already exists.
Page “Shop” already exists.
Page “Sample Page” already exists.
Page “Cart” already exists.
Page “Logout” already exists.
Page “Long Copy” already exists.
Testimonial “Lorem ipsum” already exists.
Testimonial “Lorem Ipsum” already exists.
Page “Sitemap” already exists.
Page “Brands” already exists.
Page “Specials” already exists.
Page “Featured” already exists.
Page “Newsletter” already exists.
Page “Contact Us” already exists.
Page “Shortcodes” already exists.
Page “Category Wall” already exists.
Page “Wishlist” already exists.
Page “Simple” already exists.
Page “With Camera Slider” already exists.
Page “With Category Wall” already exists.
Page “Sidebar – Left” already exists.
Page “Sidebar – Right” already exists.
Page “Buttons” already exists.
Page “Progress Bars” already exists.
Page “Panels & Alerts” already exists.
Page “Accordion Toggle & Tabs” already exists.
Page “List Item” already exists.
Page “Google Map” already exists.
Page “Sample Page” already exists.
Post “Post Format: Link” already exists.
Post “Post Format: Quote” already exists.
Post “Fusce non dui nec sem pretium at dolor” already exists.
Post “Proin nec augue id consequat” already exists.
Post “Aenean egestas congue est nec” already exists.
Post “Vivamus fringilla libero” already exists.
Post “Post Format: Gallery” already exists.
Post “Integer sit amet nisi ante” already exists.
Page “Columns” already exists.
Page “Camera Slider” already exists.
Page “Flexslider” already exists.
Page “Nivo Slider” already exists.
Page “Products Slider” already exists.
Page “Category Wall” already exists.
Page “Products Carousel” already exists.
Page “Latest Posts” already exists.
Page “Testimonial Slider” already exists.
Page “Brands Carousel” already exists.
Page “With Product Slider” already exists.
Post “Hello world!” already exists.
Product “Printed T-Shirt” already exists.
Product “Sample Top” already exists.
Product “Printed T-Shirt” already exists.
Product “Sample T-Shirt” already exists.
Product “Sample T-Shirt” already exists.
Product “Basic T-Shirt” already exists.
Failed to import pa_size L
Failed to import pa_size M
Failed to import pa_size S
Failed to import pa_size XL
Product “Sample T-Shirt” already exists.
Failed to import pa_size L
Failed to import pa_size M
Failed to import pa_size S
Failed to import pa_size XL
Product “Printed T-Shirt” already exists.
Product “Basic T-Shirt” already exists.
Product “Printed T-Shirt” already exists.
Product “Sample TShirt” already exists.
Product “Printed T-Shirt” already exists.
Product “Sample T-Shirt” already exists.
Product “Printed T-Shirt” already exists.
Product “Ladies Singlet” already exists.
Product “Basic T-Shirt” already exists.
Product “Jogging Top” already exists.
Post “Cras id purus leo” already exists.
Post “Phasellus nisl sapien” already exists.
Product “Basic Top” already exists.
Product “Basic Top” already exists.

Fatal error: Maximum execution time of 30 seconds exceeded in E:\xampp\htdocs\wordpress\wp-includes\wp-db.php on line 1868