diff --git a/wp-admin/async-upload.php b/wp-admin/async-upload.php
index f0f6dd0070..864f2be654 100644
--- a/wp-admin/async-upload.php
+++ b/wp-admin/async-upload.php
@@ -113,8 +113,8 @@ if ( isset( $_REQUEST['post_id'] ) ) {
 
 $id = media_handle_upload( 'async-upload', $post_id );
 if ( is_wp_error( $id ) ) {
-	printf(
-		'<div class="error-div error">%s <strong>%s</strong><br />%s</div>',
+	$message = sprintf(
+		'%s <strong>%s</strong><br />%s',
 		sprintf(
 			'<button type="button" class="dismiss button-link" onclick="jQuery(this).parents(\'div.media-item\').slideUp(200, function(){jQuery(this).remove();});">%s</button>',
 			__( 'Dismiss' )
@@ -126,6 +126,13 @@ if ( is_wp_error( $id ) ) {
 		),
 		esc_html( $id->get_error_message() )
 	);
+	wp_admin_notice(
+		$message,
+		array(
+			'additional_classes' => array( 'error-div', 'error' ),
+			'paragraph_wrap'     => false,
+		)
+	);
 	exit;
 }
 
diff --git a/wp-admin/edit-comments.php b/wp-admin/edit-comments.php
index 7420942f1c..262e2d9c35 100644
--- a/wp-admin/edit-comments.php
+++ b/wp-admin/edit-comments.php
@@ -301,7 +301,13 @@ if ( isset( $_REQUEST['error'] ) ) {
 			break;
 	}
 	if ( $error_msg ) {
-		echo '<div id="moderated" class="error"><p>' . $error_msg . '</p></div>';
+		wp_admin_notice(
+			$error_msg,
+			array(
+				'id'                 => 'moderated',
+				'additional_classes' => array( 'error' ),
+			)
+		);
 	}
 }
 
diff --git a/wp-admin/edit-form-advanced.php b/wp-admin/edit-form-advanced.php
index fd3bfb2165..dc3623606c 100644
--- a/wp-admin/edit-form-advanced.php
+++ b/wp-admin/edit-form-advanced.php
@@ -462,12 +462,21 @@ if ( $message ) :
 		)
 	);
 endif;
+
+$connection_lost_message = sprintf(
+	'<span class="spinner"></span> %1$s <span class="hide-if-no-sessionstorage">%2$s</span>',
+	__( '<strong>Connection lost.</strong> Saving has been disabled until you are reconnected.' ),
+	__( 'This post is being backed up in your browser, just in case.' )
+);
+
+wp_admin_notice(
+	$connection_lost_message,
+	array(
+		'id'                 => 'lost-connection-notice',
+		'additional_classes' => array( 'error', 'hidden' ),
+	)
+);
 ?>
-<div id="lost-connection-notice" class="error hidden">
-	<p><span class="spinner"></span> <?php _e( '<strong>Connection lost.</strong> Saving has been disabled until you are reconnected.' ); ?>
-	<span class="hide-if-no-sessionstorage"><?php _e( 'This post is being backed up in your browser, just in case.' ); ?></span>
-	</p>
-</div>
 <form name="post" action="post.php" method="post" id="post"
 <?php
 /**
diff --git a/wp-admin/edit-tags.php b/wp-admin/edit-tags.php
index 159ffa6847..947db5ffc5 100644
--- a/wp-admin/edit-tags.php
+++ b/wp-admin/edit-tags.php
@@ -348,9 +348,16 @@ if ( isset( $_REQUEST['s'] ) && strlen( $_REQUEST['s'] ) ) {
 
 <hr class="wp-header-end">
 
-<?php if ( $message ) : ?>
-<div id="message" class="<?php echo $class; ?> notice is-dismissible"><p><?php echo $message; ?></p></div>
-	<?php
+<?php
+if ( $message ) :
+	wp_admin_notice(
+		$message,
+		array(
+			'id'                 => 'message',
+			'additional_classes' => array( $class ),
+			'dismissible'        => true,
+		)
+	);
 	$_SERVER['REQUEST_URI'] = remove_query_arg( array( 'message', 'error' ), $_SERVER['REQUEST_URI'] );
 endif;
 ?>
diff --git a/wp-admin/import.php b/wp-admin/import.php
index 7bf1c1a135..c97a31b6ed 100644
--- a/wp-admin/import.php
+++ b/wp-admin/import.php
@@ -60,16 +60,21 @@ $parent_file = 'tools.php';
 
 <div class="wrap">
 <h1><?php echo esc_html( $title ); ?></h1>
-<?php if ( ! empty( $_GET['invalid'] ) ) : ?>
-	<div class="error">
-		<p><strong><?php _e( 'Error:' ); ?></strong>
-			<?php
-			/* translators: %s: Importer slug. */
-			printf( __( 'The %s importer is invalid or is not installed.' ), '<strong>' . esc_html( $_GET['invalid'] ) . '</strong>' );
-			?>
-		</p>
-	</div>
-<?php endif; ?>
+<?php
+if ( ! empty( $_GET['invalid'] ) ) :
+	$importer_not_installed = '<strong>' . __( 'Error:' ) . '</strong> ' . sprintf(
+		/* translators: %s: Importer slug. */
+		__( 'The %s importer is invalid or is not installed.' ),
+		'<strong>' . esc_html( $_GET['invalid'] ) . '</strong>'
+	);
+	wp_admin_notice(
+		$importer_not_installed,
+		array(
+			'additional_classes' => array( 'error' ),
+		)
+	);
+endif;
+?>
 <p><?php _e( 'If you have posts or comments in another system, WordPress can import those into this site. To get started, choose a system to import from below:' ); ?></p>
 
 <?php
diff --git a/wp-admin/nav-menus.php b/wp-admin/nav-menus.php
index 9634c2bf5c..93b3c5e635 100644
--- a/wp-admin/nav-menus.php
+++ b/wp-admin/nav-menus.php
@@ -384,7 +384,14 @@ switch ( $action ) {
 				$_nav_menu_selected_id = wp_update_nav_menu_object( 0, array( 'menu-name' => $new_menu_title ) );
 
 				if ( is_wp_error( $_nav_menu_selected_id ) ) {
-					$messages[] = '<div id="message" class="error notice is-dismissible"><p>' . $_nav_menu_selected_id->get_error_message() . '</p></div>';
+					$messages[] = wp_get_admin_notice(
+						$_nav_menu_selected_id->get_error_message(),
+						array(
+							'id'                 => 'message',
+							'additional_classes' => array( 'error' ),
+							'dismissible'        => true,
+						)
+					);
 				} else {
 					$_menu_object            = wp_get_nav_menu_object( $_nav_menu_selected_id );
 					$nav_menu_selected_id    = $_nav_menu_selected_id;
@@ -435,7 +442,14 @@ switch ( $action ) {
 					exit;
 				}
 			} else {
-				$messages[] = '<div id="message" class="error notice is-dismissible"><p>' . __( 'Please enter a valid menu name.' ) . '</p></div>';
+				$messages[] = wp_get_admin_notice(
+					__( 'Please enter a valid menu name.' ),
+					array(
+						'id'                 => 'message',
+						'additional_classes' => array( 'error' ),
+						'dismissible'        => true,
+					)
+				);
 			}
 
 			// Update existing menu.
@@ -457,7 +471,14 @@ switch ( $action ) {
 			$menu_title = trim( esc_html( $_POST['menu-name'] ) );
 
 			if ( ! $menu_title ) {
-				$messages[] = '<div id="message" class="error notice is-dismissible"><p>' . __( 'Please enter a valid menu name.' ) . '</p></div>';
+				$messages[] = wp_get_admin_notice(
+					__( 'Please enter a valid menu name.' ),
+					array(
+						'id'                 => 'message',
+						'additional_classes' => array( 'error' ),
+						'dismissible'        => true,
+					)
+				);
 				$menu_title = $_menu_object->name;
 			}
 
@@ -510,7 +531,14 @@ switch ( $action ) {
 			// Set menu locations.
 			set_theme_mod( 'nav_menu_locations', $menu_locations );
 
-			$messages[] = '<div id="message" class="updated notice is-dismissible"><p>' . __( 'Menu locations updated.' ) . '</p></div>';
+			$messages[] = wp_get_admin_notice(
+				__( 'Menu locations updated.' ),
+				array(
+					'id'                 => 'message',
+					'additional_classes' => array( 'updated' ),
+					'dismissible'        => true,
+				)
+			);
 		}
 
 		break;
diff --git a/wp-admin/plugin-editor.php b/wp-admin/plugin-editor.php
index fce25ea75c..345f0c09e0 100644
--- a/wp-admin/plugin-editor.php
+++ b/wp-admin/plugin-editor.php
@@ -29,7 +29,15 @@ if ( empty( $plugins ) ) {
 	?>
 	<div class="wrap">
 		<h1><?php echo esc_html( $title ); ?></h1>
-		<div id="message" class="error"><p><?php _e( 'No plugins are currently available.' ); ?></p></div>
+		<?php
+		wp_admin_notice(
+			__( 'No plugins are currently available.' ),
+			array(
+				'id'                 => 'message',
+				'additional_classes' => array( 'error' ),
+			)
+		);
+		?>
 	</div>
 	<?php
 	require_once ABSPATH . 'wp-admin/admin-footer.php';
diff --git a/wp-admin/plugins.php b/wp-admin/plugins.php
index ea088da98a..7ec59ae40b 100644
--- a/wp-admin/plugins.php
+++ b/wp-admin/plugins.php
@@ -339,15 +339,31 @@ if ( $action ) {
 				?>
 				<?php if ( 1 === $plugins_to_delete ) : ?>
 					<h1><?php _e( 'Delete Plugin' ); ?></h1>
-					<?php if ( $have_non_network_plugins && is_network_admin() ) : ?>
-						<div class="error"><p><strong><?php _e( 'Caution:' ); ?></strong> <?php _e( 'This plugin may be active on other sites in the network.' ); ?></p></div>
-					<?php endif; ?>
+					<?php
+					if ( $have_non_network_plugins && is_network_admin() ) :
+						$maybe_active_plugin = '<strong>' . __( 'Caution:' ) . '</strong> ' . __( 'This plugin may be active on other sites in the network.' );
+						wp_admin_notice(
+							$maybe_active_plugin,
+							array(
+								'additional_classes' => array( 'error' ),
+							)
+						);
+					endif;
+					?>
 					<p><?php _e( 'You are about to remove the following plugin:' ); ?></p>
 				<?php else : ?>
 					<h1><?php _e( 'Delete Plugins' ); ?></h1>
-					<?php if ( $have_non_network_plugins && is_network_admin() ) : ?>
-						<div class="error"><p><strong><?php _e( 'Caution:' ); ?></strong> <?php _e( 'These plugins may be active on other sites in the network.' ); ?></p></div>
-					<?php endif; ?>
+					<?php
+					if ( $have_non_network_plugins && is_network_admin() ) :
+						$maybe_active_plugins = '<strong>' . __( 'Caution:' ) . '</strong> ' . __( 'These plugins may be active on other sites in the network.' );
+						wp_admin_notice(
+							$maybe_active_plugins,
+							array(
+								'additional_classes' => array( 'error' ),
+							)
+						);
+					endif;
+					?>
 					<p><?php _e( 'You are about to remove the following plugins:' ); ?></p>
 				<?php endif; ?>
 					<ul class="ul-disc">
@@ -607,14 +623,19 @@ require_once ABSPATH . 'wp-admin/admin-header.php';
 $invalid = validate_active_plugins();
 if ( ! empty( $invalid ) ) {
 	foreach ( $invalid as $plugin_file => $error ) {
-		echo '<div id="message" class="error"><p>';
-		printf(
+		$deactivated_message = sprintf(
 			/* translators: 1: Plugin file, 2: Error message. */
 			__( 'The plugin %1$s has been deactivated due to an error: %2$s' ),
 			'<code>' . esc_html( $plugin_file ) . '</code>',
 			esc_html( $error->get_error_message() )
 		);
-		echo '</p></div>';
+		wp_admin_notice(
+			$deactivated_message,
+			array(
+				'id'                 => 'message',
+				'additional_classes' => array( 'error' ),
+			)
+		);
 	}
 }
 
diff --git a/wp-admin/theme-editor.php b/wp-admin/theme-editor.php
index 39bf5cd4fa..c9253f5bad 100644
--- a/wp-admin/theme-editor.php
+++ b/wp-admin/theme-editor.php
@@ -262,7 +262,12 @@ if ( preg_match( '/\.css$/', $file ) && ! wp_is_block_theme() && current_user_ca
 
 <?php
 if ( $theme->errors() ) {
-	echo '<div class="error"><p><strong>' . __( 'This theme is broken.' ) . '</strong> ' . $theme->errors()->get_error_message() . '</p></div>';
+	wp_admin_notice(
+		'<strong>' . __( 'This theme is broken.' ) . '</strong> ' . $theme->errors()->get_error_message(),
+		array(
+			'additional_classes' => array( 'error' ),
+		)
+	);
 }
 ?>
 
@@ -294,7 +299,12 @@ if ( $theme->errors() ) {
 
 <?php
 if ( $error ) :
-	echo '<div class="error"><p>' . __( 'File does not exist! Please double check the name and try again.' ) . '</p></div>';
+	wp_admin_notice(
+		__( 'File does not exist! Please double check the name and try again.' ),
+		array(
+			'additional_classes' => array( 'error' ),
+		)
+	);
 else :
 	?>
 	<form name="template" id="template" action="theme-editor.php" method="post">
diff --git a/wp-admin/theme-install.php b/wp-admin/theme-install.php
index ef4e4fe17f..25212974d8 100644
--- a/wp-admin/theme-install.php
+++ b/wp-admin/theme-install.php
@@ -183,9 +183,14 @@ require_once ABSPATH . 'wp-admin/admin-header.php';
 
 	<hr class="wp-header-end">
 
-	<div class="error hide-if-js">
-		<p><?php _e( 'The Theme Installer screen requires JavaScript.' ); ?></p>
-	</div>
+	<?php
+	wp_admin_notice(
+		__( 'The Theme Installer screen requires JavaScript.' ),
+		array(
+			'additional_classes' => array( 'error', 'hide-if-js' ),
+		)
+	);
+	?>
 
 	<div class="upload-theme">
 	<?php install_themes_upload(); ?>
diff --git a/wp-admin/themes.php b/wp-admin/themes.php
index 9fb3701a12..d5d8c150e3 100644
--- a/wp-admin/themes.php
+++ b/wp-admin/themes.php
@@ -345,7 +345,12 @@ if ( ! validate_current_theme() || isset( $_GET['broken'] ) ) {
 $current_theme = wp_get_theme();
 
 if ( $current_theme->errors() && ( ! is_multisite() || current_user_can( 'manage_network_themes' ) ) ) {
-	echo '<div class="error"><p>' . __( 'Error:' ) . ' ' . $current_theme->errors()->get_error_message() . '</p></div>';
+	wp_admin_notice(
+		__( 'Error:' ) . ' ' . $current_theme->errors()->get_error_message(),
+		array(
+			'additional_classes' => array( 'error' ),
+		)
+	);
 }
 
 $current_theme_actions = array();
@@ -438,79 +443,88 @@ foreach ( $themes as $theme ) :
 	<?php } ?>
 
 	<?php if ( $theme['hasUpdate'] ) : ?>
-		<?php if ( $theme['updateResponse']['compatibleWP'] && $theme['updateResponse']['compatiblePHP'] ) : ?>
-			<div class="update-message notice inline notice-warning notice-alt"><p>
-				<?php if ( $theme['hasPackage'] ) : ?>
-					<?php _e( 'New version available. <button class="button-link" type="button">Update now</button>' ); ?>
-				<?php else : ?>
-					<?php _e( 'New version available.' ); ?>
-				<?php endif; ?>
-			</p></div>
-		<?php else : ?>
-			<div class="update-message notice inline notice-error notice-alt"><p>
-				<?php
-				if ( ! $theme['updateResponse']['compatibleWP'] && ! $theme['updateResponse']['compatiblePHP'] ) {
-					printf(
-						/* translators: %s: Theme name. */
-						__( 'There is a new version of %s available, but it does not work with your versions of WordPress and PHP.' ),
-						$theme['name']
+		<?php
+		if ( $theme['updateResponse']['compatibleWP'] && $theme['updateResponse']['compatiblePHP'] ) :
+			if ( $theme['hasPackage'] ) {
+				$new_version_available = __( 'New version available. <button class="button-link" type="button">Update now</button>' );
+			} else {
+				$new_version_available = __( 'New version available.' );
+			}
+			wp_admin_notice(
+				$new_version_available,
+				array(
+					'type'               => 'warning',
+					'additional_classes' => array( 'notice-alt', 'inline', 'update-message' ),
+				)
+			);
+		else :
+			$theme_update_error = '';
+			if ( ! $theme['updateResponse']['compatibleWP'] && ! $theme['updateResponse']['compatiblePHP'] ) {
+				$theme_update_error .= sprintf(
+					/* translators: %s: Theme name. */
+					__( 'There is a new version of %s available, but it does not work with your versions of WordPress and PHP.' ),
+					$theme['name']
+				);
+				if ( current_user_can( 'update_core' ) && current_user_can( 'update_php' ) ) {
+					$theme_update_error .= sprintf(
+						/* translators: 1: URL to WordPress Updates screen, 2: URL to Update PHP page. */
+						' ' . __( '<a href="%1$s">Please update WordPress</a>, and then <a href="%2$s">learn more about updating PHP</a>.' ),
+						self_admin_url( 'update-core.php' ),
+						esc_url( wp_get_update_php_url() )
 					);
-					if ( current_user_can( 'update_core' ) && current_user_can( 'update_php' ) ) {
-						printf(
-							/* translators: 1: URL to WordPress Updates screen, 2: URL to Update PHP page. */
-							' ' . __( '<a href="%1$s">Please update WordPress</a>, and then <a href="%2$s">learn more about updating PHP</a>.' ),
-							self_admin_url( 'update-core.php' ),
-							esc_url( wp_get_update_php_url() )
-						);
-						wp_update_php_annotation( '</p><p><em>', '</em>' );
-					} elseif ( current_user_can( 'update_core' ) ) {
-						printf(
-							/* translators: %s: URL to WordPress Updates screen. */
-							' ' . __( '<a href="%s">Please update WordPress</a>.' ),
-							self_admin_url( 'update-core.php' )
-						);
-					} elseif ( current_user_can( 'update_php' ) ) {
-						printf(
-							/* translators: %s: URL to Update PHP page. */
-							' ' . __( '<a href="%s">Learn more about updating PHP</a>.' ),
-							esc_url( wp_get_update_php_url() )
-						);
-						wp_update_php_annotation( '</p><p><em>', '</em>' );
-					}
-				} elseif ( ! $theme['updateResponse']['compatibleWP'] ) {
-					printf(
-						/* translators: %s: Theme name. */
-						__( 'There is a new version of %s available, but it does not work with your version of WordPress.' ),
-						$theme['name']
+					wp_update_php_annotation( '</p><p><em>', '</em>', false );
+				} elseif ( current_user_can( 'update_core' ) ) {
+					$theme_update_error .= sprintf(
+						/* translators: %s: URL to WordPress Updates screen. */
+						' ' . __( '<a href="%s">Please update WordPress</a>.' ),
+						self_admin_url( 'update-core.php' )
 					);
-					if ( current_user_can( 'update_core' ) ) {
-						printf(
-							/* translators: %s: URL to WordPress Updates screen. */
-							' ' . __( '<a href="%s">Please update WordPress</a>.' ),
-							self_admin_url( 'update-core.php' )
-						);
-					}
-				} elseif ( ! $theme['updateResponse']['compatiblePHP'] ) {
-					printf(
-						/* translators: %s: Theme name. */
-						__( 'There is a new version of %s available, but it does not work with your version of PHP.' ),
-						$theme['name']
+				} elseif ( current_user_can( 'update_php' ) ) {
+					$theme_update_error .= sprintf(
+						/* translators: %s: URL to Update PHP page. */
+						' ' . __( '<a href="%s">Learn more about updating PHP</a>.' ),
+						esc_url( wp_get_update_php_url() )
 					);
-					if ( current_user_can( 'update_php' ) ) {
-						printf(
-							/* translators: %s: URL to Update PHP page. */
-							' ' . __( '<a href="%s">Learn more about updating PHP</a>.' ),
-							esc_url( wp_get_update_php_url() )
-						);
-						wp_update_php_annotation( '</p><p><em>', '</em>' );
-					}
+					wp_update_php_annotation( '</p><p><em>', '</em>', false );
 				}
-				?>
-			</p></div>
-		<?php endif; ?>
-	<?php endif; ?>
+			} elseif ( ! $theme['updateResponse']['compatibleWP'] ) {
+				$theme_update_error .= sprintf(
+					/* translators: %s: Theme name. */
+					__( 'There is a new version of %s available, but it does not work with your version of WordPress.' ),
+					$theme['name']
+				);
+				if ( current_user_can( 'update_core' ) ) {
+					$theme_update_error .= sprintf(
+						/* translators: %s: URL to WordPress Updates screen. */
+						' ' . __( '<a href="%s">Please update WordPress</a>.' ),
+						self_admin_url( 'update-core.php' )
+					);
+				}
+			} elseif ( ! $theme['updateResponse']['compatiblePHP'] ) {
+				$theme_update_error .= sprintf(
+					/* translators: %s: Theme name. */
+					__( 'There is a new version of %s available, but it does not work with your version of PHP.' ),
+					$theme['name']
+				);
+				if ( current_user_can( 'update_php' ) ) {
+					$theme_update_error .= sprintf(
+						/* translators: %s: URL to Update PHP page. */
+						' ' . __( '<a href="%s">Learn more about updating PHP</a>.' ),
+						esc_url( wp_get_update_php_url() )
+					);
+					wp_update_php_annotation( '</p><p><em>', '</em>', false );
+				}
+			}
+			wp_admin_notice(
+				$theme_update_error,
+				array(
+					'type'               => 'error',
+					'additional_classes' => array( 'notice-alt', 'inline', 'update-message' ),
+				)
+			);
+		endif;
+	endif;
 
-	<?php
 	if ( ! $theme['compatibleWP'] || ! $theme['compatiblePHP'] ) {
 		$message = '';
 		if ( ! $theme['compatibleWP'] && ! $theme['compatiblePHP'] ) {
@@ -566,9 +580,7 @@ foreach ( $themes as $theme ) :
 			)
 		);
 	}
-	?>
 
-	<?php
 	/* translators: %s: Theme name. */
 	$details_aria_label = sprintf( _x( 'View Theme Details for %s', 'theme' ), $theme['name'] );
 	?>
@@ -662,7 +674,9 @@ if ( ! is_multisite() && $broken_themes ) {
 			<td></td>
 		<?php } ?>
 	</tr>
-	<?php foreach ( $broken_themes as $broken_theme ) : ?>
+	<?php
+	foreach ( $broken_themes as $broken_theme ) :
+		?>
 		<tr>
 			<td><?php echo $broken_theme->get( 'Name' ) ? $broken_theme->display( 'Name' ) : esc_html( $broken_theme->get_stylesheet() ); ?></td>
 			<td><?php echo $broken_theme->errors()->get_error_message(); ?></td>
@@ -723,7 +737,9 @@ if ( ! is_multisite() && $broken_themes ) {
 			}
 			?>
 		</tr>
-	<?php endforeach; ?>
+		<?php
+	endforeach;
+	?>
 </table>
 </div>
 
diff --git a/wp-admin/update-core.php b/wp-admin/update-core.php
index 28f92ca303..acd6cf7bf7 100644
--- a/wp-admin/update-core.php
+++ b/wp-admin/update-core.php
@@ -1072,16 +1072,22 @@ if ( 'upgrade-core' === $action ) {
 		if ( 'themes' === $upgrade_error ) {
 			$theme_updates = get_theme_updates();
 			if ( ! empty( $theme_updates ) ) {
-				echo '<div class="error"><p>';
-				_e( 'Please select one or more themes to update.' );
-				echo '</p></div>';
+				wp_admin_notice(
+					__( 'Please select one or more themes to update.' ),
+					array(
+						'additional_classes' => array( 'error' ),
+					)
+				);
 			}
 		} else {
 			$plugin_updates = get_plugin_updates();
 			if ( ! empty( $plugin_updates ) ) {
-				echo '<div class="error"><p>';
-				_e( 'Please select one or more plugins to update.' );
-				echo '</p></div>';
+				wp_admin_notice(
+					__( 'Please select one or more plugins to update.' ),
+					array(
+						'additional_classes' => array( 'error' ),
+					)
+				);
 			}
 		}
 	}
diff --git a/wp-admin/user-edit.php b/wp-admin/user-edit.php
index f89e4e5ea0..642b0185c4 100644
--- a/wp-admin/user-edit.php
+++ b/wp-admin/user-edit.php
@@ -244,11 +244,12 @@ switch ( $action ) {
 		endif;
 
 		if ( isset( $errors ) && is_wp_error( $errors ) ) {
-			?>
-			<div class="error">
-				<p><?php echo implode( "</p>\n<p>", $errors->get_error_messages() ); ?></p>
-			</div>
-			<?php
+			wp_admin_notice(
+				implode( "</p>\n<p>", $errors->get_error_messages() ),
+				array(
+					'additional_classes' => array( 'error' ),
+				)
+			);
 		}
 		?>
 
diff --git a/wp-admin/user-new.php b/wp-admin/user-new.php
index b516f4f460..7ef33a8132 100644
--- a/wp-admin/user-new.php
+++ b/wp-admin/user-new.php
@@ -381,17 +381,19 @@ if ( current_user_can( 'create_users' ) ) {
 ?>
 </h1>
 
-<?php if ( isset( $errors ) && is_wp_error( $errors ) ) : ?>
-	<div class="error">
-		<ul>
-		<?php
-		foreach ( $errors->get_error_messages() as $err ) {
-			echo "<li>$err</li>\n";
-		}
-		?>
-		</ul>
-	</div>
-	<?php
+<?php
+if ( isset( $errors ) && is_wp_error( $errors ) ) :
+	$error_message = '';
+	foreach ( $errors->get_error_messages() as $err ) {
+		$error_message .= "<li>$err</li>\n";
+	}
+	wp_admin_notice(
+		'<ul>' . $error_message . '</ul>',
+		array(
+			'additional_classes' => array( 'error' ),
+			'paragraph_wrap'     => false,
+		)
+	);
 endif;
 
 if ( ! empty( $messages ) ) {
@@ -408,15 +410,21 @@ if ( ! empty( $messages ) ) {
 }
 ?>
 
-<?php if ( isset( $add_user_errors ) && is_wp_error( $add_user_errors ) ) : ?>
-	<div class="error">
-		<?php
-		foreach ( $add_user_errors->get_error_messages() as $message ) {
-			echo "<p>$message</p>";
-		}
-		?>
-	</div>
-<?php endif; ?>
+<?php
+if ( isset( $add_user_errors ) && is_wp_error( $add_user_errors ) ) :
+	$error_message = '';
+	foreach ( $add_user_errors->get_error_messages() as $message ) {
+		$error_message .= "<p>$message</p>\n";
+	}
+	wp_admin_notice(
+		$error_message,
+		array(
+			'additional_classes' => array( 'error' ),
+			'paragraph_wrap'     => false,
+		)
+	);
+endif;
+?>
 <div id="ajax-response"></div>
 
 <?php
diff --git a/wp-admin/users.php b/wp-admin/users.php
index 717f487c5c..bab7ad5196 100644
--- a/wp-admin/users.php
+++ b/wp-admin/users.php
@@ -339,11 +339,16 @@ switch ( $wp_list_table->current_action() ) {
 		<div class="wrap">
 		<h1><?php _e( 'Delete Users' ); ?></h1>
 
-		<?php if ( isset( $_REQUEST['error'] ) ) : ?>
-			<div class="error">
-				<p><strong><?php _e( 'Error:' ); ?></strong> <?php _e( 'Please select an option.' ); ?></p>
-			</div>
-		<?php endif; ?>
+		<?php
+		if ( isset( $_REQUEST['error'] ) ) :
+			wp_admin_notice(
+				'<strong>' . __( 'Error:' ) . '</strong> ' . __( 'Please select an option.' ),
+				array(
+					'additional_classes' => array( 'error' ),
+				)
+			);
+		endif;
+		?>
 
 		<?php if ( 1 === count( $all_user_ids ) ) : ?>
 			<p><?php _e( 'You have specified this user for deletion:' ); ?></p>
@@ -742,17 +747,18 @@ switch ( $wp_list_table->current_action() ) {
 		endif;
 		?>
 
-		<?php if ( isset( $errors ) && is_wp_error( $errors ) ) : ?>
-			<div class="error">
-				<ul>
-				<?php
-				foreach ( $errors->get_error_messages() as $err ) {
-					echo "<li>$err</li>\n";
-				}
-				?>
-				</ul>
-			</div>
-			<?php
+		<?php
+		if ( isset( $errors ) && is_wp_error( $errors ) ) :
+			$error_message = '';
+			foreach ( $errors->get_error_messages() as $err ) {
+				$error_message .= "<li>$err</li>\n";
+			}
+			wp_admin_notice(
+				'<ul>' . $error_message . '</ul>',
+				array(
+					'additional_classes' => array( 'error' ),
+				)
+			);
 		endif;
 
 		if ( ! empty( $messages ) ) {
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 1a3388a73a..4e8bfc2334 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.4-alpha-56599';
+$wp_version = '6.4-alpha-56600';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.