diff --git a/.travis.yml b/.travis.yml
deleted file mode 100644
index 60551c76..00000000
--- a/.travis.yml
+++ /dev/null
@@ -1,49 +0,0 @@
-#
-# This file is part of phpFastCache.
-#
-# @license MIT License (MIT)
-#
-# For full copyright and license information, please see the docs/CREDITS.txt file.
-#
-# @author Georges.L (Geolim4)  <contact@geolim4.com>
-# @author Contributors  https://github.com/PHPSocialNetwork/phpfastcache/graphs/contributors
-#
-os: linux
-dist: bionic
-language: php
-
-services:
-  - memcached
-  - redis
-cache:
-  directories:
-    - $HOME/pecl_cache
-php:
-  - 8.0
-  - 8.1
-  - 8.2
-jobs:
-  fast_finish: true
-  allow_failures:
-    - php: nightly
-
-before_install:
-  - sudo apt remove cmake
-  - pip install cmake --upgrade
-  - phpenv config-add bin/ci/php_common.ini
-  - phpenv config-rm xdebug.ini
-  - composer install
-  - composer require phwoolcon/ci-pecl-cacher -n
-  - "./bin/ci/scripts/install_ssdb.sh || echo \"SSDB install failed\""
-  - "./bin/ci/scripts/install_couchbase.sh || echo \"Couchbase install failed\""
-  - "./bin/ci/scripts/setup_gcp.sh || echo \"GCP setup failed\""
-  - "pecl channel-update pecl.php.net || echo \"PECL Channel update failed\""
-  - "yes | ./vendor/bin/ci-pecl-install memcache || echo \"PECL Memcache install failed\""
-  - "yes | ./vendor/bin/ci-pecl-install memcached || echo \"PECL Memcached install failed\""
-  - "yes | ./vendor/bin/ci-pecl-install couchbase-3.2.2 couchbase || echo \"PECL Couchbase install failed\"" # @todo UPGRADE TO COUCHBASE 4.x.x once we upgraded from Bionic to Focal
-install:
-  - ./bin/ci/scripts/install_dependencies.sh
-
-script:
-  - composer run-script quality
-  - composer run-script tests
diff --git a/lib/Phpfastcache/CacheContract.php b/lib/Phpfastcache/CacheContract.php
index 1a5f0362..0d0d80c3 100644
--- a/lib/Phpfastcache/CacheContract.php
+++ b/lib/Phpfastcache/CacheContract.php
@@ -32,7 +32,7 @@ public function __construct(CacheItemPoolInterface $cacheInstance)
     /**
      * @throws InvalidArgumentException
      */
-    public function get(string|\Stringable $cacheKey, callable $callback, DateInterval|int $expiresAfter = null): mixed
+    public function get(string|\Stringable $cacheKey, callable $callback, DateInterval|int|null $expiresAfter = null): mixed
     {
         $cacheItem = $this->cacheInstance->getItem((string) $cacheKey);
 
@@ -54,7 +54,7 @@ public function get(string|\Stringable $cacheKey, callable $callback, DateInterv
     /**
      * @throws InvalidArgumentException
      */
-    public function __invoke(string $cacheKey, callable $callback, DateInterval|int $expiresAfter = null): mixed
+    public function __invoke(string $cacheKey, callable $callback, DateInterval|int|null $expiresAfter = null): mixed
     {
         return $this->get($cacheKey, $callback, $expiresAfter);
     }
diff --git a/lib/Phpfastcache/Cluster/AggregatorInterface.php b/lib/Phpfastcache/Cluster/AggregatorInterface.php
index c14a3c72..5364ee6d 100644
--- a/lib/Phpfastcache/Cluster/AggregatorInterface.php
+++ b/lib/Phpfastcache/Cluster/AggregatorInterface.php
@@ -86,7 +86,7 @@ public function getCluster(int $strategy): ClusterPoolInterface;
      *
      * @return void
      */
-    public function aggregateDriverByName(string $driverName, ConfigurationOption $driverConfig = null): void;
+    public function aggregateDriverByName(string $driverName, ?ConfigurationOption $driverConfig = null): void;
 
     /**
      * @param AggregatablePoolInterface $driverPool
diff --git a/lib/Phpfastcache/Cluster/ClusterAggregator.php b/lib/Phpfastcache/Cluster/ClusterAggregator.php
index 6f080e01..69df214f 100644
--- a/lib/Phpfastcache/Cluster/ClusterAggregator.php
+++ b/lib/Phpfastcache/Cluster/ClusterAggregator.php
@@ -94,7 +94,7 @@ public function aggregateDriver(AggregatablePoolInterface $driverPool): void
      * @throws PhpfastcacheDriverNotFoundException
      * @throws PhpfastcacheLogicException
      */
-    public function aggregateDriverByName(string $driverName, ConfigurationOption $driverConfig = null): void
+    public function aggregateDriverByName(string $driverName, ?ConfigurationOption $driverConfig = null): void
     {
         if (isset($this->cluster)) {
             throw new PhpfastcacheLogicException('The cluster has been already build, cannot aggregate more pools.');
diff --git a/lib/Phpfastcache/Drivers/Redis/Config.php b/lib/Phpfastcache/Drivers/Redis/Config.php
index 1d43e784..f87536d3 100644
--- a/lib/Phpfastcache/Drivers/Redis/Config.php
+++ b/lib/Phpfastcache/Drivers/Redis/Config.php
@@ -98,7 +98,7 @@ public function getDatabase(): ?int
      * @return static
      * @throws PhpfastcacheLogicException
      */
-    public function setDatabase(int $database = null): static
+    public function setDatabase(?int $database = null): static
     {
         return $this->setProperty('database', $database);
     }
diff --git a/lib/Phpfastcache/Exceptions/PhpfastcacheIOException.php b/lib/Phpfastcache/Exceptions/PhpfastcacheIOException.php
index 38ed42df..52284009 100644
--- a/lib/Phpfastcache/Exceptions/PhpfastcacheIOException.php
+++ b/lib/Phpfastcache/Exceptions/PhpfastcacheIOException.php
@@ -24,7 +24,7 @@ class PhpfastcacheIOException extends PhpfastcacheCoreException
     /**
      * @inheritdoc
      */
-    public function __construct(string $message = "", int $code = 0, \Throwable $previous = null)
+    public function __construct(string $message = "", int $code = 0, ?\Throwable $previous = null)
     {
         $lastError = error_get_last();
         if ($lastError) {
diff --git a/lib/Phpfastcache/Helper/Psr16Adapter.php b/lib/Phpfastcache/Helper/Psr16Adapter.php
index f201ea30..fbed034f 100644
--- a/lib/Phpfastcache/Helper/Psr16Adapter.php
+++ b/lib/Phpfastcache/Helper/Psr16Adapter.php
@@ -49,7 +49,7 @@ class Psr16Adapter implements CacheInterface
      * @throws PhpfastcacheDriverException
      * @throws PhpfastcacheDriverNotFoundException
      */
-    public function __construct(string|ExtendedCacheItemPoolInterface $driver, ConfigurationOptionInterface $config = null)
+    public function __construct(string|ExtendedCacheItemPoolInterface $driver, ?ConfigurationOptionInterface $config = null)
     {
         if ($driver instanceof ExtendedCacheItemPoolInterface) {
             if ($config !== null) {