Source

File: wp-admin/includes/class-wp-site-health-auto-updates.php

function test_if_failed_update() {
		$failed = get_site_option( 'auto_core_update_failed' );

		if ( ! $failed ) {
			return false;
		}

		if ( ! empty( $failed['critical'] ) ) {
			$description  = __( 'A previous automatic background update ended with a critical failure, so updates are now disabled.' );
			$description .= ' ' . __( 'You would have received an email because of this.' );
			$description .= ' ' . __( "When you've been able to update using the \"Update Now\" button on Dashboard > Updates, we'll clear this error for future update attempts." );
			$description .= ' ' . sprintf(
				/* translators: %s: Code of error shown. */
				__( 'The error code was %s.' ),
				'<code>' . $failed['error_code'] . '</code>'
			);
			return array(
				'description' => $description,
				'severity'    => 'warning',
			);
		}

		$description = __( 'A previous automatic background update could not occur.' );
		if ( empty( $failed['retry'] ) ) {
			$description .= ' ' . __( 'You would have received an email because of this.' );
		}

		$description .= ' ' . __( "We'll try again with the next release." );
		$description .= ' ' . sprintf(
			/* translators: %s: Code of error shown. */
			__( 'The error code was %s.' ),
			'<code>' . $failed['error_code'] . '</code>'
		);
		return array(
			'description' => $description,
			'severity'    => 'warning',
		);
	}