Gallery crash

Hello crystyan18,
please add this code in functions.php file.

function ms_image_editor_default_to_gd( $editors ) {
 $gd_editor = 'WP_Image_Editor_GD';

 $editors = array_diff( $editors, array( $gd_editor ) );
 array_unshift( $editors, $gd_editor );

 return $editors;
}
add_filter( 'wp_image_editors', 'ms_image_editor_default_to_gd' );

Hope this will solve your problem.

Thanks.