diff --git a/assets/js/admin-script.js b/assets/js/admin-script.js
index d61c6734..426f988d 100644
--- a/assets/js/admin-script.js
+++ b/assets/js/admin-script.js
@@ -478,7 +478,7 @@ jQuery( function( $ ) {
 						default: // for other XML extensions
 							let xml         = response.data.preview_data;
 							let xml_escaped = xml.replace( /&/g,'&amp;' ).replace( /</g,'&lt;' ).replace( />/g,'&gt;' ).replace( / /g, '&nbsp;' ).replace( /\n/g,'<br />' );
-							$preview.html( '<div id="preview-xml" class="preview-'+response.data.output_format+'">'+xml_escaped+'</div>' );
+							$preview.html( '<div id="preview-xml" class="preview-' + response.data.output_format + '">' + xml_escaped + '</div>' );
 							break;
 					}
 				}
diff --git a/includes/Documents/OrderDocument.php b/includes/Documents/OrderDocument.php
index 073be303..378823bc 100644
--- a/includes/Documents/OrderDocument.php
+++ b/includes/Documents/OrderDocument.php
@@ -1395,7 +1395,7 @@ public function output_html() {
 	 *
 	 * @param string $output_format
 	 * @param XMLDocument $xml_document
-	 * @return void
+	 * @return mixed
 	 */
 	public function preview_xml( string $output_format, XMLDocument $xml_document ) {
 		// get last settings
@@ -1409,9 +1409,9 @@ public function preview_xml( string $output_format, XMLDocument $xml_document )
 	 *
 	 * @param XMLDocument $xml_document
 	 * @param boolean $contents_only
-	 * @return void
+	 * @return mixed
 	 */
-	public function output_xml( XMLDocument $xml_document, $contents_only = false ) {
+	public function output_xml( XMLDocument $xml_document, bool $contents_only = false ) {
 		$xml_maker = wcpdf_get_xml_maker();
 
 		$xml_document->set_order( $this->order );
diff --git a/includes/Main.php b/includes/Main.php
index ff718c9d..3cc3ccb4 100644
--- a/includes/Main.php
+++ b/includes/Main.php
@@ -542,7 +542,7 @@ public function generate_document_ajax() {
 						$document->output_pdf( $output_mode );
 						break;
 					default: // custom output
-						do_action( 'wpo_wcpdf_document_output', $document, $output_format );
+						do_action( 'wpo_wcpdf_document_custom_output', $document, $output_format );
 						break;
 				}
 			} else {
diff --git a/woocommerce-pdf-invoices-packingslips.php b/woocommerce-pdf-invoices-packingslips.php
index d39f0084..f58a21c3 100644
--- a/woocommerce-pdf-invoices-packingslips.php
+++ b/woocommerce-pdf-invoices-packingslips.php
@@ -144,6 +144,7 @@ public function includes() {
 
 		// plugin functions
 		include_once $this->plugin_path() . '/wpo-ips-functions.php';
+		include_once $this->plugin_path() . '/wpo-ips-deprecated-functions.php';
 
 		// Third party compatibility
 		$this->third_party_plugins = \WPO\IPS\Compatibility\ThirdPartyPlugins::instance();
diff --git a/wpo-ips-deprecated-functions.php b/wpo-ips-deprecated-functions.php
new file mode 100644
index 00000000..7db776b2
--- /dev/null
+++ b/wpo-ips-deprecated-functions.php
@@ -0,0 +1,16 @@
+<?php
+
+if ( ! defined( 'ABSPATH' ) ) {
+	exit;
+}
+
+/**
+ * Get UBL Maker
+ * Legacy function < v3.9.1
+ *
+ * @return WPO\IPS\Makers\XMLMaker
+ */
+function wcpdf_get_ubl_maker() {
+	wcpdf_deprecated_function( 'wcpdf_get_ubl_maker', '3.9.1', 'wcpdf_get_xml_maker' );
+	return wcpdf_get_xml_maker();
+}
\ No newline at end of file
diff --git a/wpo-ips-functions.php b/wpo-ips-functions.php
index 84b87cfd..5db7819d 100644
--- a/wpo-ips-functions.php
+++ b/wpo-ips-functions.php
@@ -181,17 +181,6 @@ function wcpdf_get_xml_maker() {
 	return new $class();
 }
 
-/**
- * Get UBL Maker
- * Legacy function < v3.9.2
- *
- * @return WPO\IPS\Makers\XMLMaker
- */
-function wcpdf_get_ubl_maker() {
-	wcpdf_deprecated_function( 'wcpdf_get_ubl_maker', '3.9.2', 'wcpdf_get_xml_maker' );
-	return wcpdf_get_xml_maker();
-}
-
 /**
  * Check if UBL is available
  *