diff --git a/.gitignore b/.gitignore
index c7b6d033..862001b9 100644
--- a/.gitignore
+++ b/.gitignore
@@ -166,3 +166,10 @@ pip-log.txt
 
 # Mac crap
 .DS_Store
+
+
+#############
+## Composer
+#############
+
+vendor/
diff --git a/QuickBooks/Driver/Sql.php b/QuickBooks/Driver/Sql.php
index 74e400a1..9615c1a2 100755
--- a/QuickBooks/Driver/Sql.php
+++ b/QuickBooks/Driver/Sql.php
@@ -1111,7 +1111,7 @@ protected function _recurDequeue($user, $by_priority = false)
 
 		if ($by_priority)
 		{
-			$sql .= ' ORDER BY priority DESC ';
+			$sql .= ' ORDER BY priority DESC, enqueue_datetime ASC, quickbooks_recur_id ASC ';
 		}
 
 		if ($arr = $this->_fetch($this->_query($sql . ' ', $errnum, $errmsg, 0, 1)))
@@ -1430,7 +1430,8 @@ protected function _queueDequeue($user, $by_priority = false)
 
 		if ($by_priority)
 		{
-			$sql .= ' ORDER BY priority DESC, ident ASC ';
+		  // Run highest priority first, then preference older queue entries. In case datetime is the same use queue ID to infer earlier entry.
+			$sql .= ' ORDER BY priority DESC, enqueue_datetime ASC, quickbooks_queue_id ASC ';
 		}
 
 		return $this->_fetch($this->_query($sql, $errnum, $errmsg, 0, 1));
diff --git a/QuickBooks/Driver/Sql/Mysqli.php b/QuickBooks/Driver/Sql/Mysqli.php
index fe856210..a9e6adb6 100644
--- a/QuickBooks/Driver/Sql/Mysqli.php
+++ b/QuickBooks/Driver/Sql/Mysqli.php
@@ -430,8 +430,9 @@ public function escape($str)
 	 */
 	protected function _escape($str)
 	{
-		if (is_array($str))
-		{
+	  if ($str === null) {
+      $str = '';
+    } elseif (is_array($str)) {
 			error_log('Param passed to _escape($str) was an array: ' . print_r($str, true));
 			$str = '';
 		}
diff --git a/QuickBooks/Payments.php b/QuickBooks/Payments.php
index efa65495..ae44b26b 100755
--- a/QuickBooks/Payments.php
+++ b/QuickBooks/Payments.php
@@ -102,8 +102,9 @@ class Quickbooks_Payments
 	protected $_last_errdetail;
 	protected $_last_errtype;
 	protected $_last_errinfolink;
+    private mixed $_last_intuittid;
 
-	public function __construct($oauth_consumer_key, $oauth_consumer_secret, $sandbox = false, $dsn = null, $log_level = QUICKBOOKS_LOG_NORMAL)
+    public function __construct($oauth_consumer_key, $oauth_consumer_secret, $sandbox = false, $dsn = null, $log_level = QUICKBOOKS_LOG_NORMAL)
 	{
 		$this->_oauth_consumer_key = $oauth_consumer_key;
 		$this->_oauth_consumer_secret = $oauth_consumer_secret;
diff --git a/QuickBooks/UnitTest.php b/QuickBooks/UnitTest.php
index 74dc1a35..8dbe7c60 100755
--- a/QuickBooks/UnitTest.php
+++ b/QuickBooks/UnitTest.php
@@ -19,8 +19,9 @@ class QuickBooks_UnitTest
 	protected $__lastMessage;
 	protected $__lastActual;
 	protected $__lastExpected;
-	
-	public function __construct()
+    private mixed $__lastError;
+
+    public function __construct()
 	{
 		
 	}
diff --git a/QuickBooks/Utilities.php b/QuickBooks/Utilities.php
index c90ece51..08c3bb4e 100755
--- a/QuickBooks/Utilities.php
+++ b/QuickBooks/Utilities.php
@@ -90,7 +90,12 @@ static public function mask($message)
 			if (substr($key, 0, 1) == '<')
 			{
 				// It's an XML tag
-				$contents = QuickBooks_Utilities::_extractTagContents(trim($key, '<> '), $message);
+				$contents = QuickBooks_XML::extractTagContents(trim($key, '<> '), $message);
+
+				// Clears type coercion warning in PHP 8+
+				if (!$contents) {
+				  $contents = '';
+        }
 				
 				$masked = str_repeat('x', min(strlen($contents), 12)) . substr($contents, 12);
 				
@@ -101,15 +106,6 @@ static public function mask($message)
 		return $message;
 	}
 	
-	/**
-	 * @deprecated		Use QuickBooks_XML::extractTagContents() instead
-	 */
-	static protected function _extractTagContents($tag, $data)
-	{
-		$tmp = QuickBooks_XML::extractTagContents($tag, $data);
-		return $tmp;
-	}
-	
 	/**
 	 * Write a message to the log (via the back-end driver) 
 	 * 
diff --git a/QuickBooks/WebConnector/Handlers.php b/QuickBooks/WebConnector/Handlers.php
index 3348875d..7932a49b 100755
--- a/QuickBooks/WebConnector/Handlers.php
+++ b/QuickBooks/WebConnector/Handlers.php
@@ -320,6 +320,8 @@ protected function _defaults($config)
 			'deny_reallyfast_timeout' => 600,
 
 			'masking' => true,
+
+      'status_error_threshold' => 500, // the lowest status code considered an error
 			);
 
 		$config = array_merge($defaults, $config);
@@ -347,6 +349,8 @@ protected function _defaults($config)
 		$config['deny_reallyfast_logins'] = (boolean) $config['deny_reallyfast_logins'];
 		$config['deny_reallyfast_timeout'] = (int) max(1, $config['deny_reallyfast_timeout']);
 
+    $config['status_error_threshold'] = (int) max(1, $config['status_error_threshold']);
+
 		return $config;
 	}
 
@@ -518,14 +522,14 @@ public function authenticate($obj)
 			}
 		}
 
-		// Custom authentication backends
-		$override_dsn = $this->_config['authenticate'];
-
 		if (!empty($this->_config['authenticate_dsn']))
 		{
 			// Backwards compat.
 			$override_dsn = $this->_config['authenticate_dsn'];
-		}
+		} else {
+      // Custom authentication backends
+      $override_dsn = $this->_config['authenticate'];
+    }
 
 		$auth = null;
 
@@ -544,7 +548,7 @@ public function authenticate($obj)
 		$customauth_wait_before_next_update = null;
 		$customauth_min_run_every_n_seconds = null;
 
-		if (is_array($override_dsn) or strlen($override_dsn)) 	// Custom autj
+		if (is_array($override_dsn) or ($override_dsn !== null and strlen($override_dsn))) 	// Custom autj
 		{
 			//if ($auth->authenticate($obj->strUserName, $obj->strPassword, $customauth_company_file, $customauth_wait_before_next_update, $customauth_min_run_every_n_seconds) and
 
@@ -1288,7 +1292,8 @@ public function receiveResponseXML($obj)
 
 			// Check if we got a error message...
 			if (strlen($obj->message) or
-				$this->_extractStatusCode($obj->response)) // or an error code
+          $this->_extractStatusCode($obj->response)
+          >= $this->_config['status_error_threshold']) // or an error code
 			{
 				//$this->_log('Extracted code[' . $this->_extractStatusCode($obj->response) . ']', $obj->ticket, QUICKBOOKS_LOG_DEBUG);
 
diff --git a/QuickBooks/WebConnector/Queue.php b/QuickBooks/WebConnector/Queue.php
index 3168d4f3..82e2f7f3 100755
--- a/QuickBooks/WebConnector/Queue.php
+++ b/QuickBooks/WebConnector/Queue.php
@@ -60,8 +60,13 @@ class QuickBooks_WebConnector_Queue
 	 * @var string
 	 */
 	protected $_user;
-	
-	/**
+
+    /**
+     * @var object|null
+     */
+    private $_driver;
+
+    /**
 	 * Create a new QuickBooks queue instance
 	 * 
 	 * @param mixed $dsn_or_conn	A DSN-style connection string (i.e.: mysq://root:pass@locahost/database) or a database connection (if you wish to re-use an existing database connection)
@@ -198,7 +203,7 @@ public function recurring($run_every, $action, $ident = null, $priority = 0, $ex
 	 * called. 
 	 * 
 	 * @param string $action		An action to be performed within QuickBooks (see the qbXML and QuickBooks SDK documentation, i.e.: "CustomerAdd", "InvoiceAdd", "CustomerMod", etc.)
-	 * @param mixed $ident			A unique identifier (if required) for a record being operated on (i.e. if you're doing a "CustomerAdd", you'd probaly put a unique customer ID number here, so you're SOAP handler function knows which customer it is supposed to add)
+	 * @param mixed $ident			A unique identifier (if required) for a record being operated on (i.e. if you're doing a "CustomerAdd", you'd probably put a unique customer ID number here, so your SOAP handler function knows which customer it is supposed to add)
 	 * @param integer $priority		The priority of the update (higher priority actions will be pushed to QuickBooks before lower priority actions)
 	 * @param array $extra			If you need to make additional bits of data available to your request/response functions, you can pass an array of extra data here
 	 * @param string $user			The username of the QuickBooks Web Connector user this item should be queued for 
@@ -207,7 +212,8 @@ public function recurring($run_every, $action, $ident = null, $priority = 0, $ex
 	 */	
 	public function enqueue($action, $ident = null, $priority = 0, $extra = null, $user = null, $qbxml = null, $replace = true)
 	{
-		if (!strlen($ident))
+	  // strlen(null) generates depreciation warning in PHP8
+		if ($ident === null || !strlen($ident))
 		{
 			// If they didn't provide an $ident, generate a random, unique one
 			
diff --git a/QuickBooks/XML.php b/QuickBooks/XML.php
index b58ec3c5..a839acf5 100755
--- a/QuickBooks/XML.php
+++ b/QuickBooks/XML.php
@@ -214,7 +214,7 @@ class QuickBooks_XML
 	 * 
 	 * @param string $tag		The XML tag to extract the contents from 
 	 * @param string $data		The XML document
-	 * @return string			The contents of the tag
+	 * @return string|null			The contents of the tag
 	 */	
 	static public function extractTagContents($tag, $data)
 	{
diff --git a/QuickBooks/XML/Backend/Builtin.php b/QuickBooks/XML/Backend/Builtin.php
index 76849412..b4a829dd 100644
--- a/QuickBooks/XML/Backend/Builtin.php
+++ b/QuickBooks/XML/Backend/Builtin.php
@@ -364,6 +364,11 @@ protected function _parseHelper($xml, &$Root, &$errnum, &$errmsg, $indent = 0)
 			$length = $node[3];
 			$payload = $node[4];
 
+			// Force type coercion for PHP 8.1 warnings but also compatible with PHP 5.0
+			if ($payload === null) {
+			  $payload = '';
+      }
+
 			$tmp = '';
 			$attributes = array();
 			$this->_extractAttributes($tag_w_attrs, $tmp, $attributes);
@@ -371,6 +376,10 @@ protected function _parseHelper($xml, &$Root, &$errnum, &$errmsg, $indent = 0)
 			$Node = new QuickBooks_XML_Node($tag);
 			foreach ($attributes as $key => $value)
 			{
+        // Force type coercion for PHP 8.1 warnings but also compatible with PHP 5.0
+			  if ($value === null) {
+			    $value = '';
+        }
 				$value = QuickBooks_XML::decode($value, true);
 				
 				$Node->addAttribute($key, $value);
diff --git a/composer.json b/composer.json
index d7a21d8b..c4b14583 100644
--- a/composer.json
+++ b/composer.json
@@ -14,7 +14,7 @@
         }
     ],
     "require": {
-        "php": ">=5.0.0"
+        "php": "^5.0|^7.0|^8.0"
     },
 
     "autoload": {
diff --git a/composer.lock b/composer.lock
new file mode 100644
index 00000000..2ffd588c
--- /dev/null
+++ b/composer.lock
@@ -0,0 +1,20 @@
+{
+    "_readme": [
+        "This file locks the dependencies of your project to a known state",
+        "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
+        "This file is @generated automatically"
+    ],
+    "content-hash": "eac6704a48f10e32485644cf1c9bb943",
+    "packages": [],
+    "packages-dev": [],
+    "aliases": [],
+    "minimum-stability": "stable",
+    "stability-flags": [],
+    "prefer-stable": false,
+    "prefer-lowest": false,
+    "platform": {
+        "php": ">=5.0.0"
+    },
+    "platform-dev": [],
+    "plugin-api-version": "2.0.0"
+}
diff --git a/docs/web_connector/example_codeigniter_web_connector/models/quickbooks.php b/docs/web_connector/example_codeigniter_web_connector/models/quickbooks.php
index 627a76e5..ea1a7411 100644
--- a/docs/web_connector/example_codeigniter_web_connector/models/quickbooks.php
+++ b/docs/web_connector/example_codeigniter_web_connector/models/quickbooks.php
@@ -2,7 +2,9 @@
 
 class Quickbooks extends CI_Model
 {
-	public function __construct()
+    private $_dsn;
+
+    public function __construct()
 	{
 		parent::__construct();
 	}
diff --git a/docs/web_connector/example_kohana_web_connector/application/classes/model/qbdata.php b/docs/web_connector/example_kohana_web_connector/application/classes/model/qbdata.php
index 8a27816e..cfffbff7 100644
--- a/docs/web_connector/example_kohana_web_connector/application/classes/model/qbdata.php
+++ b/docs/web_connector/example_kohana_web_connector/application/classes/model/qbdata.php
@@ -12,7 +12,9 @@
  */
 class Model_Qbdata extends ORM {
 
-	public function __construct()
+    private $_db;
+
+    public function __construct()
 	{
 		//link up this model to our qb_data database
 		$this->_db = Database::instance('qb_data');