Create “images” folder in current active theme the put “default-image.jpg” in that folder.
<?php
if ( has_post_thumbnail( ) ) {
echo get_the_post_thumbnail( $page->ID, 'image' );
} else { ?>
<img src="<?php echo get_template_directory_uri().'/images/default-image.jpg'; ?>"/>
<?php } ?>
Use path according to the theme (parent or child).
-
get_stylesheet_directory_uri(): url path to current Theme directory -
get_template_directory_uri(): url path to parent Theme directory