diff --git a/wp-admin/includes/class-wp-site-health-auto-updates.php b/wp-admin/includes/class-wp-site-health-auto-updates.php
index 1ddaa05feb..d1c133524d 100644
--- a/wp-admin/includes/class-wp-site-health-auto-updates.php
+++ b/wp-admin/includes/class-wp-site-health-auto-updates.php
@@ -273,7 +273,7 @@ class WP_Site_Health_Auto_Updates {
 	 * @return array The test results.
 	 */
 	function test_check_wp_filesystem_method() {
-		// Make sure the `request_filesystem_credentials` function is available during our REST call.
+		// Make sure the `request_filesystem_credentials()` function is available during our REST API call.
 		if ( ! function_exists( 'request_filesystem_credentials' ) ) {
 			require_once ABSPATH . '/wp-admin/includes/file.php';
 		}
@@ -324,7 +324,7 @@ class WP_Site_Health_Auto_Updates {
 			return false;
 		}
 
-		// Make sure the `get_core_checksums` function is available during our REST call.
+		// Make sure the `get_core_checksums()` function is available during our REST API call.
 		if ( ! function_exists( 'get_core_checksums' ) ) {
 			require_once ABSPATH . '/wp-admin/includes/update.php';
 		}
diff --git a/wp-admin/includes/file.php b/wp-admin/includes/file.php
index 97cef303c1..98e0f4962c 100644
--- a/wp-admin/includes/file.php
+++ b/wp-admin/includes/file.php
@@ -2369,6 +2369,12 @@ function request_filesystem_credentials( $form_post, $type = '', $error = false,
 			echo '<input type="hidden" name="' . esc_attr( $field ) . '" value="' . esc_attr( $submitted_form[ $field ] ) . '" />';
 		}
 	}
+
+	// Make sure the `submit_button()` function is available during the REST API call
+	// from WP_Site_Health_Auto_Updates::test_check_wp_filesystem_method().
+	if ( ! function_exists( 'submit_button' ) ) {
+		require_once ABSPATH . '/wp-admin/includes/template.php';
+	}
 	?>
 	<p class="request-filesystem-credentials-action-buttons">
 		<?php wp_nonce_field( 'filesystem-credentials', '_fs_nonce', false, true ); ?>
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 9c08cebb5f..3888297ab6 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.8-alpha-50978';
+$wp_version = '5.8-alpha-50979';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.