diff --git a/.github/workflows/php.yml b/.github/workflows/php.yml
index ad3362944..dcd49a8c6 100644
--- a/.github/workflows/php.yml
+++ b/.github/workflows/php.yml
@@ -29,7 +29,7 @@ jobs:
       run: |
         echo "key=$(date +'%Y-%U')" >> $GITHUB_ENV
 
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - uses: gacts/run-and-post-run@v1
       id: post-run-command
@@ -59,7 +59,7 @@ jobs:
         key: ${{ env.key }}
 
     - name: Cache extensions
-      uses: actions/cache@v3
+      uses: actions/cache@v4
       with:
         path: ${{ steps.extcache.outputs.dir }}
         key: ${{ steps.extcache.outputs.key }}
@@ -78,7 +78,7 @@ jobs:
 
     - name: Cache Composer packages
       id: composer-cache
-      uses: actions/cache@v3
+      uses: actions/cache@v4
       with:
         path: vendor
         key: ${{ runner.os }}-${{ matrix.php-version }}-php-${{ hashFiles('**/composer.json') }}
@@ -86,7 +86,7 @@ jobs:
           ${{ runner.os }}-${{ matrix.php-version }}-php-
     - name: Cache test tools
       id: test-tools-cache
-      uses: actions/cache@v3
+      uses: actions/cache@v4
       with:
         path: vendor-bin
         key: ${{ runner.os }}-${{ matrix.php-version }}-php-${{ hashFiles('**/composer.json') }}
diff --git a/src/Extension/Propagator/B3/B3MultiPropagator.php b/src/Extension/Propagator/B3/B3MultiPropagator.php
index 7c5211261..5d4afbed9 100644
--- a/src/Extension/Propagator/B3/B3MultiPropagator.php
+++ b/src/Extension/Propagator/B3/B3MultiPropagator.php
@@ -103,7 +103,7 @@ public function fields(): array
     }
 
     /** {@inheritdoc} */
-    public function inject(&$carrier, PropagationSetterInterface $setter = null, ContextInterface $context = null): void
+    public function inject(&$carrier, ?PropagationSetterInterface $setter = null, ?ContextInterface $context = null): void
     {
         $setter ??= ArrayAccessGetterSetter::getInstance();
         $context ??= Context::getCurrent();
@@ -125,7 +125,7 @@ public function inject(&$carrier, PropagationSetterInterface $setter = null, Con
         }
     }
 
-    public function extract($carrier, PropagationGetterInterface $getter = null, ContextInterface $context = null): ContextInterface
+    public function extract($carrier, ?PropagationGetterInterface $getter = null, ?ContextInterface $context = null): ContextInterface
     {
         $getter ??= ArrayAccessGetterSetter::getInstance();
         $context ??= Context::getCurrent();
diff --git a/src/Extension/Propagator/B3/B3Propagator.php b/src/Extension/Propagator/B3/B3Propagator.php
index 1c91c6145..0d8c720dc 100644
--- a/src/Extension/Propagator/B3/B3Propagator.php
+++ b/src/Extension/Propagator/B3/B3Propagator.php
@@ -42,13 +42,13 @@ public function fields(): array
     }
 
     /** {@inheritdoc} */
-    public function inject(&$carrier, PropagationSetterInterface $setter = null, ContextInterface $context = null): void
+    public function inject(&$carrier, ?PropagationSetterInterface $setter = null, ?ContextInterface $context = null): void
     {
         $this->propagator->inject($carrier, $setter, $context);
     }
 
     /** {@inheritdoc} */
-    public function extract($carrier, PropagationGetterInterface $getter = null, ContextInterface $context = null): ContextInterface
+    public function extract($carrier, ?PropagationGetterInterface $getter = null, ?ContextInterface $context = null): ContextInterface
     {
         $getter ??= ArrayAccessGetterSetter::getInstance();
         $context ??= Context::getCurrent();
diff --git a/src/Extension/Propagator/B3/B3SinglePropagator.php b/src/Extension/Propagator/B3/B3SinglePropagator.php
index 56160ff1a..7b9ab1ed0 100644
--- a/src/Extension/Propagator/B3/B3SinglePropagator.php
+++ b/src/Extension/Propagator/B3/B3SinglePropagator.php
@@ -55,7 +55,7 @@ public function fields(): array
     }
 
     /** {@inheritdoc} */
-    public function inject(&$carrier, PropagationSetterInterface $setter = null, ContextInterface $context = null): void
+    public function inject(&$carrier, ?PropagationSetterInterface $setter = null, ?ContextInterface $context = null): void
     {
         $setter ??= ArrayAccessGetterSetter::getInstance();
         $context ??= Context::getCurrent();
@@ -78,7 +78,7 @@ public function inject(&$carrier, PropagationSetterInterface $setter = null, Con
     }
 
     /** {@inheritdoc} */
-    public function extract($carrier, PropagationGetterInterface $getter = null, ContextInterface $context = null): ContextInterface
+    public function extract($carrier, ?PropagationGetterInterface $getter = null, ?ContextInterface $context = null): ContextInterface
     {
         $getter ??= ArrayAccessGetterSetter::getInstance();
         $context ??= Context::getCurrent();
diff --git a/src/Extension/Propagator/CloudTrace/CloudTracePropagator.php b/src/Extension/Propagator/CloudTrace/CloudTracePropagator.php
index 5e2cf7787..7a53e3f12 100644
--- a/src/Extension/Propagator/CloudTrace/CloudTracePropagator.php
+++ b/src/Extension/Propagator/CloudTrace/CloudTracePropagator.php
@@ -57,7 +57,7 @@ public function fields(): array
     }
 
     /** {@inheritdoc} */
-    public function inject(&$carrier, PropagationSetterInterface $setter = null, ContextInterface $context = null): void
+    public function inject(&$carrier, ?PropagationSetterInterface $setter = null, ?ContextInterface $context = null): void
     {
         if ($this->oneWay) {
             return;
@@ -76,7 +76,7 @@ public function inject(&$carrier, PropagationSetterInterface $setter = null, Con
     }
 
     /** {@inheritdoc} */
-    public function extract($carrier, PropagationGetterInterface $getter = null, ContextInterface $context = null): ContextInterface
+    public function extract($carrier, ?PropagationGetterInterface $getter = null, ?ContextInterface $context = null): ContextInterface
     {
         $getter ??= ArrayAccessGetterSetter::getInstance();
         $context ??= Context::getCurrent();
diff --git a/src/Extension/Propagator/Jaeger/JaegerBaggagePropagator.php b/src/Extension/Propagator/Jaeger/JaegerBaggagePropagator.php
index a7a2b6c9b..dd53b2238 100644
--- a/src/Extension/Propagator/Jaeger/JaegerBaggagePropagator.php
+++ b/src/Extension/Propagator/Jaeger/JaegerBaggagePropagator.php
@@ -39,7 +39,7 @@ public function fields(): array
     }
 
     /** {@inheritdoc} */
-    public function inject(&$carrier, PropagationSetterInterface $setter = null, ContextInterface $context = null): void
+    public function inject(&$carrier, ?PropagationSetterInterface $setter = null, ?ContextInterface $context = null): void
     {
         $setter ??= ArrayAccessGetterSetter::getInstance();
         $context ??= Context::getCurrent();
@@ -59,7 +59,7 @@ public function inject(&$carrier, PropagationSetterInterface $setter = null, Con
     }
 
     /** {@inheritdoc} */
-    public function extract($carrier, PropagationGetterInterface $getter = null, ContextInterface $context = null): ContextInterface
+    public function extract($carrier, ?PropagationGetterInterface $getter = null, ?ContextInterface $context = null): ContextInterface
     {
         $getter ??= ArrayAccessGetterSetter::getInstance();
         $context ??= Context::getCurrent();
diff --git a/src/Extension/Propagator/Jaeger/JaegerPropagator.php b/src/Extension/Propagator/Jaeger/JaegerPropagator.php
index 3064c57e8..31cdcd576 100644
--- a/src/Extension/Propagator/Jaeger/JaegerPropagator.php
+++ b/src/Extension/Propagator/Jaeger/JaegerPropagator.php
@@ -51,7 +51,7 @@ public function fields(): array
     }
 
     /** {@inheritdoc} */
-    public function inject(&$carrier, PropagationSetterInterface $setter = null, ContextInterface $context = null): void
+    public function inject(&$carrier, ?PropagationSetterInterface $setter = null, ?ContextInterface $context = null): void
     {
         $setter ??= ArrayAccessGetterSetter::getInstance();
         $context ??= Context::getCurrent();
@@ -75,7 +75,7 @@ public function inject(&$carrier, PropagationSetterInterface $setter = null, Con
     }
 
     /** {@inheritdoc} */
-    public function extract($carrier, PropagationGetterInterface $getter = null, ContextInterface $context = null): ContextInterface
+    public function extract($carrier, ?PropagationGetterInterface $getter = null, ?ContextInterface $context = null): ContextInterface
     {
         $getter ??= ArrayAccessGetterSetter::getInstance();
         $context ??= Context::getCurrent();