Header image in blog post gone twenty ten

this is so be design – if the ‘featured’ image of a post is larger than a set width, it will get taken as the header image for that single post (similar for static pages).

try and use a smaller image as featured image.

alternatively, you will need to edit header.php in a child theme, to remove this automatic header image replacement code.

Thanks for the fast answer! So, concerning the featured image – I never did anything different with my latest post, than before. So this is strange.

Concerning the changes to the header.php – I found this snippet:

<?php
// Check if this is a post or page, if it has a thumbnail, and if it’s a big one
if ( is_singular() && current_theme_supports( ‘post-thumbnails’ ) &&
has_post_thumbnail( $post->ID ) &&
( /* $src, $width, $height */ $image = wp_get_attachment_image_src( get_post_thumbnail_id( $post->ID ), ‘post-thumbnail’ ) ) &&
$image[1] >= HEADER_IMAGE_WIDTH ) :
// Houston, we have a new header image!
echo get_the_post_thumbnail( $post->ID );
elseif ( get_header_image() ) : ?>
<img src=”<?php header_image(); ?>” width=”<?php echo HEADER_IMAGE_WIDTH; ?>” height=”<?php echo HEADER_IMAGE_HEIGHT; ?>” alt=”” />

You think the changes should be made here?

Thanks again for your help!
Lilly

that is the right section to edit (in the child theme);

for example, change it to:

<?php if ( get_header_image() ) : ?>
<img src="<?php header_image(); ?>" width="<?php echo HEADER_IMAGE_WIDTH; ?>" height="<?php echo HEADER_IMAGE_HEIGHT; ?>" alt="" />

caveat:
not tested;
it is recommended to make a backup copy before editing – https://codex.www.ads-software.com/WordPress_Backups