Fatal error

Do you have the plugin network-wide active and did you add a new site in your network?

The plugin is network-active and I didn’t add any new sites.

The part with the language is strange. Do you make use of the hook that overrides the blog-collection?

I’m not sure, it’s been a while since I installed the plugin for the first time. How can I check that?

Look into your functions.php … maybe there is a filter-function that begins with ‘msls..’.

There’s this:

}
function my_msls_blog_collection_get( $arr ) {
    $arr = array();
    foreach ( array( 1, 2, 3, ) as $id ) {
        $arr[$id] = get_blog_details( $id );
    }
    return $arr;
}
add_filter( 'msls_blog_collection_construct', 'my_msls_blog_collection_get' );
function my_print_something() {
    $blogs  = MslsBlogCollection::instance();
    $mydata = MslsOptions::create();
    foreach ( $blogs->get_objects() as $blog ) {
        $language = $blog->get_language();
        if ( $blog->userblog_id == $blogs->get_current_blog_id() ) {
            $url = $mydata->get_current_link();
        }
        else {
            switch_to_blog( $blog->userblog_id );
            if ( 'MslsOptions' != get_class( $mydata ) && !$mydata->has_value( $language ) ) {
                restore_current_blog();
                continue;
            }
            $url = $mydata->get_permalink( $language );
            restore_current_blog();
        }
        $language = substr( $language, 0, 2 );
        printf(
            '<link rel="alternate" hreflang="%s" href="%s" />',
            ( 'us' == $language ? 'en' : $language ),
            $url
        );
    }
}

Neither this code nor the language settings had changed around the time that the errors occured for the first time, though.

OK, so you have 3 sites (with the blog_id 1, 2 and 3)? Please check this first!

That is correct. The default blog has id 1, the other two blogs are correctly connected via Network -> Settings -> Domains

I cannot help if I don’t get answers ?? … you have a site with the id 1, another with the id 2 and another with the id 3? Correct?

If yes, please comment the filter first like this:

//add_filter( 'msls_blog_collection_construct', 'my_msls_blog_collection_get' );

Let me know,
Dennis.

I cannot help if I don’t get answers ??

I thought I did that with “That is correct.” ??

Commenting out that line got rid of the error popping up when trying to edit/ save a post. It also returned the hreflang-tag on the home page of the default blog. The home pages of blog id 2 and 3 now have a double hreflang reference – both to the domain itself.

Cross post references (both links and hreflang connections, between interlinked posts and pages) still aren’t present.

OK, please comment out also the filter for “my_print_something” …

The entire function, from [function my_print_something()] to the end?

No, there should be an add_action for that.

//add_action( 'wp_head', 'my_print_something' );

Just tried that – I don’t see any changes or consequences.

This should have an effect to the HTML-header.