error adding a video url

hello

When i try to add video or playlist shows this error:

Oops... there seems to be a problem saving the thumbnail. Most likely you need to install a PHP image processing library, such as GD or Imagick. Please send the following information to the developer if the problem persists.
WP_Error Object
(
    [errors:WP_Error:private] => Array
        (
            [invalid_image] => Array
                (
                    [0] => File is not an image.
                )

        )

    [error_data:WP_Error:private] => Array
        (
            [invalid_image] => https://img.youtube.com/vi/LDYjenC5J9g/0.jpg
        )

)

please tell me if there is an easy fix to this.

thanks

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