diff --git a/.travis.yml b/.travis.yml
index 6fed0af..16e11ad 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,13 +1,11 @@
 language: php
 
 php:
-  - 5.5
-  - 5.6
-  - 7.0
+  - 7.3
   - hhvm
 
 env:
-  - GUZZLE_VERSION="6.1.1"
+  - GUZZLE_VERSION="7.0.1"
 
 before_script: composer install
 
@@ -18,4 +16,4 @@ matrix:
   allow_failures:
     - php: hhvm
     - php: 7.0
-  fast_finish: true
\ No newline at end of file
+  fast_finish: true
diff --git a/composer.json b/composer.json
index 2ef5179..d1415b5 100755
--- a/composer.json
+++ b/composer.json
@@ -11,11 +11,11 @@
   "homepage": "http://developer.constantcontact.com",
   "license": "MIT",
   "require": {
-    "php": ">=5.5.0",
-    "guzzlehttp/guzzle": "^6.1.1"
+    "php": ">=7.3",
+    "guzzlehttp/guzzle": "^7.0"
   },
   "require-dev": {
-    "phpunit/phpunit": "4.8.21"
+    "phpunit/phpunit": "^9.0"
   },
   "authors": [
     {
diff --git a/src/Ctct/Services/BaseService.php b/src/Ctct/Services/BaseService.php
index 7f7e666..e99c57e 100755
--- a/src/Ctct/Services/BaseService.php
+++ b/src/Ctct/Services/BaseService.php
@@ -102,7 +102,7 @@ protected function convertException($exception) {
             $ctctException = new CtctException("Something went wrong", $exception->getCode());
         }
         $ctctException->setUrl($exception->getRequest()->getUri());
-        $ctctException->setErrors(json_decode($exception->getResponse()->getBody()->getContents()));
+        $ctctException->setErrors(json_decode($exception->getResponse()->getBody()->getContents(), true));
         return $ctctException;
     }
 }
diff --git a/test/Auth/CtctOAuth2UnitTest.php b/test/Auth/CtctOAuth2UnitTest.php
index 504ee46..478c236 100644
--- a/test/Auth/CtctOAuth2UnitTest.php
+++ b/test/Auth/CtctOAuth2UnitTest.php
@@ -7,7 +7,7 @@
 use GuzzleHttp\HandlerStack;
 use GuzzleHttp\Psr7\Response;
 
-class CtctOAuth2UnitTest extends PHPUnit_Framework_TestCase {
+class CtctOAuth2UnitTest extends \PHPUnit\Framework\TestCase {
     /**
      * @var Client
      */
@@ -22,7 +22,7 @@ class CtctOAuth2UnitTest extends PHPUnit_Framework_TestCase {
     private $clientSecret = "clientSecret";
     private $redirectUri = "redirectUri";
 
-    public static function setUpBeforeClass() {
+    public static function setUpBeforeClass() : void {
         $mock = new MockHandler([
             new Response(200, array(), JsonLoader::getTokenInfoJson()),
             new Response(200, array(), JsonLoader::getAccessTokenJson())
@@ -31,7 +31,7 @@ public static function setUpBeforeClass() {
         self::$client = new Client(['handler' => $handler]);
     }
 
-    public function setUp() {
+    public function setUp() : void {
         $this->ctctOAuth2 = new CtctOAuth2($this->apiKey, $this->clientSecret, $this->redirectUri);
     }
 
diff --git a/test/Services/AccountServiceUnitTest.php b/test/Services/AccountServiceUnitTest.php
index b908569..a0bdd48 100644
--- a/test/Services/AccountServiceUnitTest.php
+++ b/test/Services/AccountServiceUnitTest.php
@@ -7,13 +7,13 @@
 use GuzzleHttp\HandlerStack;
 use GuzzleHttp\Psr7\Response;
 
-class AccountServiceUnitTest extends PHPUnit_Framework_TestCase {
+class AccountServiceUnitTest extends \PHPUnit\Framework\TestCase {
     /**
      * @var Client
      */
     private static $client;
 
-    public static function setUpBeforeClass() {
+    public static function setUpBeforeClass() : void {
         $mock = new MockHandler([
             new Response(200, array(), JsonLoader::getVerifiedAddressesJson()),
             new Response(200, array(), JsonLoader::getAccountInfoJson())
diff --git a/test/Services/ActivityServiceUnitTest.php b/test/Services/ActivityServiceUnitTest.php
index e0140ca..ffea200 100644
--- a/test/Services/ActivityServiceUnitTest.php
+++ b/test/Services/ActivityServiceUnitTest.php
@@ -5,13 +5,13 @@
 use GuzzleHttp\HandlerStack;
 use GuzzleHttp\Psr7\Response;
 
-class ActivityServiceUnitTest extends PHPUnit_Framework_TestCase {
+class ActivityServiceUnitTest extends \PHPUnit\Framework\TestCase {
     /**
      * @var Client
      */
     private static $client;
 
-    public static function setUpBeforeClass() {
+    public static function setUpBeforeClass() : void {
         $mock = new MockHandler([
             new Response(200, array(), JsonLoader::getActivity()),
             new Response(200, array(), JsonLoader::getActivities()),
diff --git a/test/Services/CampaignScheduleServiceUnitTest.php b/test/Services/CampaignScheduleServiceUnitTest.php
index bae62fd..9dedf01 100755
--- a/test/Services/CampaignScheduleServiceUnitTest.php
+++ b/test/Services/CampaignScheduleServiceUnitTest.php
@@ -8,13 +8,13 @@
 use GuzzleHttp\HandlerStack;
 use GuzzleHttp\Psr7\Response;
 
-class CampaignScheduleServiceUnitTest extends PHPUnit_Framework_TestCase {
+class CampaignScheduleServiceUnitTest extends \PHPUnit\Framework\TestCase {
     /**
      * @var Client
      */
     private static $client;
 
-    public static function setUpBeforeClass() {
+    public static function setUpBeforeClass() : void {
         self::$client = new Client();
         $scheduleJson = JsonLoader::getCampaignScheduleJson();
         $mock = new MockHandler([
diff --git a/test/Services/CampaignTrackingServiceUnitTest.php b/test/Services/CampaignTrackingServiceUnitTest.php
index 7bc5d9f..e8bb55f 100755
--- a/test/Services/CampaignTrackingServiceUnitTest.php
+++ b/test/Services/CampaignTrackingServiceUnitTest.php
@@ -13,13 +13,13 @@
 use GuzzleHttp\HandlerStack;
 use GuzzleHttp\Psr7\Response;
 
-class CampaignTrackingServiceUnitTest extends PHPUnit_Framework_TestCase {
+class CampaignTrackingServiceUnitTest extends \PHPUnit\Framework\TestCase {
     /**
      * @var Client
      */
     private static $client;
 
-    public static function setUpBeforeClass() {
+    public static function setUpBeforeClass() : void {
         $mock = new MockHandler([
             new Response(200, array(), JsonLoader::getBounces()),
             new Response(200, array(), JsonLoader::getClicks()),
diff --git a/test/Services/ContactServiceUnitTest.php b/test/Services/ContactServiceUnitTest.php
index 6f3cdeb..ba85592 100755
--- a/test/Services/ContactServiceUnitTest.php
+++ b/test/Services/ContactServiceUnitTest.php
@@ -8,13 +8,13 @@
 use GuzzleHttp\HandlerStack;
 use GuzzleHttp\Psr7\Response;
 
-class ContactServiceUnitTest extends PHPUnit_Framework_TestCase {
+class ContactServiceUnitTest extends \PHPUnit\Framework\TestCase {
     /**
      * @var ConstantContact
      */
     private static $constantContact;
 
-    public static function setUpBeforeClass() {
+    public static function setUpBeforeClass() : void {
         $contactJson = JsonLoader::getContactJson();
         $mock = new MockHandler([
             new Response(200, array(), JsonLoader::getContactsJson()),
diff --git a/test/Services/ContactTrackingServiceUnitTest.php b/test/Services/ContactTrackingServiceUnitTest.php
index ee8807b..cba4d0f 100755
--- a/test/Services/ContactTrackingServiceUnitTest.php
+++ b/test/Services/ContactTrackingServiceUnitTest.php
@@ -13,13 +13,13 @@
 use GuzzleHttp\HandlerStack;
 use GuzzleHttp\Psr7\Response;
 
-class ContactTrackingServiceUnitTest extends PHPUnit_Framework_TestCase {
+class ContactTrackingServiceUnitTest extends \PHPUnit\Framework\TestCase {
     /**
      * @var Client
      */
     private static $client;
 
-    public static function setUpBeforeClass() {
+    public static function setUpBeforeClass() : void {
         $mock = new MockHandler([
             new Response(200, array(), JsonLoader::getBounces()),
             new Response(200, array(), JsonLoader::getClicks()),
diff --git a/test/Services/EmailCampaignServiceUnitTest.php b/test/Services/EmailMarketingServiceUnitTest.php
similarity index 99%
rename from test/Services/EmailCampaignServiceUnitTest.php
rename to test/Services/EmailMarketingServiceUnitTest.php
index e477a3b..4339ce4 100755
--- a/test/Services/EmailCampaignServiceUnitTest.php
+++ b/test/Services/EmailMarketingServiceUnitTest.php
@@ -9,13 +9,13 @@
 use GuzzleHttp\HandlerStack;
 use GuzzleHttp\Psr7\Response;
 
-class EmailMarketingServiceUnitTest extends PHPUnit_Framework_TestCase {
+class EmailMarketingServiceUnitTest extends \PHPUnit\Framework\TestCase {
     /**
      * @var Client
      */
     private static $client;
 
-    public static function setUpBeforeClass() {
+    public static function setUpBeforeClass() : void {
         $getCampaignJson = JsonLoader::getCampaignJson();
         $mock = new MockHandler([
             new Response(200, array(), JsonLoader::getCampaignsJson()),
diff --git a/test/Services/LibraryServiceUnitTest.php b/test/Services/LibraryServiceUnitTest.php
index f3773f2..19591d8 100644
--- a/test/Services/LibraryServiceUnitTest.php
+++ b/test/Services/LibraryServiceUnitTest.php
@@ -9,13 +9,13 @@
 use GuzzleHttp\HandlerStack;
 use GuzzleHttp\Psr7\Response;
 
-class LibraryServiceUnitTest extends PHPUnit_Framework_TestCase {
+class LibraryServiceUnitTest extends \PHPUnit\Framework\TestCase {
     /**
      * @var Client
      */
     private static $client;
 
-    public static function setUpBeforeClass() {
+    public static function setUpBeforeClass() : void {
         $mock = new MockHandler([
             new Response(200, array(), JsonLoader::getLibraryFileJson()),
             new Response(200, array(), JsonLoader::getLibraryFilesJson()),
@@ -180,4 +180,4 @@ public function testGetFileUploadStatus() {
         $this->assertEquals("Active", $fileUploadStatus->description);
         $this->assertEquals("Active", $fileUploadStatus->status);
     }
-}
\ No newline at end of file
+}
diff --git a/test/Services/ListServiceUnitTest.php b/test/Services/ListServiceUnitTest.php
index ea34b57..1c33add 100755
--- a/test/Services/ListServiceUnitTest.php
+++ b/test/Services/ListServiceUnitTest.php
@@ -8,13 +8,13 @@
 use GuzzleHttp\HandlerStack;
 use GuzzleHttp\Psr7\Response;
 
-class ListServiceUnitTest extends PHPUnit_Framework_TestCase {
+class ListServiceUnitTest extends \PHPUnit\Framework\TestCase {
     /**
      * @var Client
      */
     private static $client;
 
-    public static function setUpBeforeClass() {
+    public static function setUpBeforeClass() : void {
         self::$client = new Client();
         $getListStream = JsonLoader::getListJson();
         $mock = new MockHandler([