diff --git a/wp-admin/includes/class-language-pack-upgrader.php b/wp-admin/includes/class-language-pack-upgrader.php
index 6f7cf742bd..89b9f9ac87 100644
--- a/wp-admin/includes/class-language-pack-upgrader.php
+++ b/wp-admin/includes/class-language-pack-upgrader.php
@@ -383,7 +383,7 @@ class Language_Pack_Upgrader extends WP_Upgrader {
 			case 'theme':
 				$theme = wp_get_theme( $update->slug );
 				if ( $theme->exists() ) {
-					return $theme->Get( 'Name' );
+					return $theme->get( 'Name' );
 				}
 				break;
 			case 'plugin':
diff --git a/wp-admin/includes/class-wp-automatic-updater.php b/wp-admin/includes/class-wp-automatic-updater.php
index 4dccd94ccd..2facbeb1d5 100644
--- a/wp-admin/includes/class-wp-automatic-updater.php
+++ b/wp-admin/includes/class-wp-automatic-updater.php
@@ -411,7 +411,7 @@ class WP_Automatic_Updater {
 			case 'theme':
 				$upgrader_item = $item->theme;
 				$theme         = wp_get_theme( $upgrader_item );
-				$item_name     = $theme->Get( 'Name' );
+				$item_name     = $theme->get( 'Name' );
 				// Add the current version so that it can be reported in the notification email.
 				$item->current_version = $theme->get( 'Version' );
 				if ( empty( $item->current_version ) ) {
diff --git a/wp-admin/includes/class-wp-filesystem-ftpsockets.php b/wp-admin/includes/class-wp-filesystem-ftpsockets.php
index 9a37d88c11..986fccf2cf 100644
--- a/wp-admin/includes/class-wp-filesystem-ftpsockets.php
+++ b/wp-admin/includes/class-wp-filesystem-ftpsockets.php
@@ -77,7 +77,7 @@ class WP_Filesystem_ftpsockets extends WP_Filesystem_Base {
 			return false;
 		}
 
-		$this->ftp->setTimeout( FS_CONNECT_TIMEOUT );
+		$this->ftp->SetTimeout( FS_CONNECT_TIMEOUT );
 
 		if ( ! $this->ftp->SetServer( $this->options['hostname'], $this->options['port'] ) ) {
 			$this->errors->add(
@@ -120,7 +120,7 @@ class WP_Filesystem_ftpsockets extends WP_Filesystem_Base {
 
 		$this->ftp->SetType( FTP_BINARY );
 		$this->ftp->Passive( true );
-		$this->ftp->setTimeout( FS_TIMEOUT );
+		$this->ftp->SetTimeout( FS_TIMEOUT );
 
 		return true;
 	}
diff --git a/wp-admin/includes/post.php b/wp-admin/includes/post.php
index 40fac43d6e..ebdd61df34 100644
--- a/wp-admin/includes/post.php
+++ b/wp-admin/includes/post.php
@@ -2186,7 +2186,7 @@ function wp_autosave( $post_data ) {
  *
  * @param int $post_id Optional. Post ID.
  */
-function redirect_post( $post_id = '' ) {
+function redirect_post( $post_id = 0 ) {
 	if ( isset( $_POST['save'] ) || isset( $_POST['publish'] ) ) {
 		$status = get_post_status( $post_id );
 
diff --git a/wp-admin/includes/taxonomy.php b/wp-admin/includes/taxonomy.php
index 7765084fa7..359cfafe2f 100644
--- a/wp-admin/includes/taxonomy.php
+++ b/wp-admin/includes/taxonomy.php
@@ -75,7 +75,7 @@ function wp_create_category( $cat_name, $category_parent = 0 ) {
  * @param int      $post_id    Optional. The post ID. Default empty.
  * @return int[] Array of IDs of categories assigned to the given post.
  */
-function wp_create_categories( $categories, $post_id = '' ) {
+function wp_create_categories( $categories, $post_id = 0 ) {
 	$cat_ids = array();
 	foreach ( $categories as $category ) {
 		$id = category_exists( $category );
diff --git a/wp-includes/block-template.php b/wp-includes/block-template.php
index affae1c09a..eecbe2d61d 100644
--- a/wp-includes/block-template.php
+++ b/wp-includes/block-template.php
@@ -253,7 +253,7 @@ function get_the_block_template_html() {
 		if ( is_user_logged_in() ) {
 			return '<h1>' . esc_html__( 'No matching template found' ) . '</h1>';
 		}
-		return;
+		return '';
 	}
 
 	$content = $wp_embed->run_shortcode( $_wp_current_template_content );
diff --git a/wp-includes/category-template.php b/wp-includes/category-template.php
index b950fab70b..b2c88c9c25 100644
--- a/wp-includes/category-template.php
+++ b/wp-includes/category-template.php
@@ -793,7 +793,7 @@ function wp_tag_cloud( $args = '' ) {
  * @return int Scaled count.
  */
 function default_topic_count_scale( $count ) {
-	return round( log10( $count + 1 ) * 100 );
+	return (int) round( log10( $count + 1 ) * 100 );
 }
 
 /**
diff --git a/wp-includes/class-wp-block-pattern-categories-registry.php b/wp-includes/class-wp-block-pattern-categories-registry.php
index 3d37a5940a..2d5fbcf2fe 100644
--- a/wp-includes/class-wp-block-pattern-categories-registry.php
+++ b/wp-includes/class-wp-block-pattern-categories-registry.php
@@ -107,7 +107,7 @@ final class WP_Block_Pattern_Categories_Registry {
 	 * @since 5.5.0
 	 *
 	 * @param string $category_name Pattern category name including namespace.
-	 * @return array Registered pattern properties.
+	 * @return array|null Registered pattern properties, or `null` if the pattern category is not registered.
 	 */
 	public function get_registered( $category_name ) {
 		if ( ! $this->is_registered( $category_name ) ) {
diff --git a/wp-includes/class-wp-block-patterns-registry.php b/wp-includes/class-wp-block-patterns-registry.php
index 3b5f053bfd..2afa8a853f 100644
--- a/wp-includes/class-wp-block-patterns-registry.php
+++ b/wp-includes/class-wp-block-patterns-registry.php
@@ -188,7 +188,7 @@ final class WP_Block_Patterns_Registry {
 	 * @since 5.5.0
 	 *
 	 * @param string $pattern_name Block pattern name including namespace.
-	 * @return array Registered pattern properties.
+	 * @return array|null Registered pattern properties or `null` if the pattern is not registered.
 	 */
 	public function get_registered( $pattern_name ) {
 		if ( ! $this->is_registered( $pattern_name ) ) {
diff --git a/wp-includes/class-wp-block-styles-registry.php b/wp-includes/class-wp-block-styles-registry.php
index 9a990173b4..8fb5e2eb23 100644
--- a/wp-includes/class-wp-block-styles-registry.php
+++ b/wp-includes/class-wp-block-styles-registry.php
@@ -140,7 +140,7 @@ final class WP_Block_Styles_Registry {
 	 *
 	 * @param string $block_name       Block type name including namespace.
 	 * @param string $block_style_name Block style name.
-	 * @return array Registered block style properties.
+	 * @return array|null Registered block style properties or `null` if the block style is not registered.
 	 */
 	public function get_registered( $block_name, $block_style_name ) {
 		if ( ! $this->is_registered( $block_name, $block_style_name ) ) {
diff --git a/wp-includes/pluggable.php b/wp-includes/pluggable.php
index c6a0c6e24e..9fd6d1d00d 100644
--- a/wp-includes/pluggable.php
+++ b/wp-includes/pluggable.php
@@ -446,10 +446,10 @@ if ( ! function_exists( 'wp_mail' ) ) :
 							$phpmailer->addAddress( $address, $recipient_name );
 							break;
 						case 'cc':
-							$phpmailer->addCc( $address, $recipient_name );
+							$phpmailer->addCC( $address, $recipient_name );
 							break;
 						case 'bcc':
-							$phpmailer->addBcc( $address, $recipient_name );
+							$phpmailer->addBCC( $address, $recipient_name );
 							break;
 						case 'reply_to':
 							$phpmailer->addReplyTo( $address, $recipient_name );
diff --git a/wp-includes/script-loader.php b/wp-includes/script-loader.php
index d439629882..fac13c604c 100644
--- a/wp-includes/script-loader.php
+++ b/wp-includes/script-loader.php
@@ -396,7 +396,7 @@ function wp_default_packages_inline_scripts( $scripts ) {
 			"\n",
 			array(
 				'( function() {',
-				'	var userId = ' . get_current_user_ID() . ';',
+				'	var userId = ' . get_current_user_id() . ';',
 				'	var storageKey = "WP_DATA_USER_" + userId;',
 				'	wp.data',
 				'		.use( wp.data.plugins.persistence, { storageKey: storageKey } );',
diff --git a/wp-includes/version.php b/wp-includes/version.php
index a4d35d2b58..6e8679960d 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.9-alpha-60274';
+$wp_version = '6.9-alpha-60275';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.