I'm trying to move a site to a new Ubuntu server, and enable HTTP2 in the process. This means I've had (I think) to switch to php-fpm.

The only issue is with the custom blocks in the theme - anywhere one of these has been added to a page I see the error

Your site doesn’t include support for the "[my-block/name]" block. 
You can leave this block intact or remove it entirely.

If I turn on WP debug I get a couple of deprecation warnings repeated several times:

Deprecated:  strpos(): Passing null to parameter #1 ($haystack) of type string is deprecated in /var/www/html/wp-includes/functions.php on line 7241

which is the second line here:

function wp_is_stream( $path ) {
    $scheme_separator = strpos( $path, '://' );


Deprecated:  str_replace(): Passing null to parameter #3 ($subject) of type array|string is deprecated in /var/www/html/wp-includes/functions.php on line 2187

which is the second line here (in function wp_normalize_path):

// Standardize all paths to use '/'.
$path = str_replace( '\\', '/', $path );

No idea if these are pertinent? Does anyone know how I might start debugging this issue with the custom blocks?

**EDIT: ** These deprecation warnings happen throughout WP admin, so I suspect they're not the root of my issue.

  • What versions of PHP and WordPress are you using? Commented Nov 29, 2023 at 13:02
  • Latest WordPress, PHP8.1 Commented Nov 29, 2023 at 13:39

1 Answer 1


Argh, totally my error - I'm using ACF Pro to manage our custom blocks, but I'd only installed the free (not Pro) version on the new server, so block registration was not completing. Installing ACF Pro fixed the issue.

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