diff --git a/src/Component/Analytics/Analytics.php b/src/Component/Analytics/Analytics.php
index 5eca02f9d..c8a1db938 100644
--- a/src/Component/Analytics/Analytics.php
+++ b/src/Component/Analytics/Analytics.php
@@ -180,8 +180,7 @@ public function addGrouping(Grouping $grouping): self
     /**
      * {@inheritdoc}
      */
-    #[\ReturnTypeWillChange]
-    public function jsonSerialize()
+    public function jsonSerialize(): mixed
     {
         return array_filter([
             'functions' => $this->functions,
diff --git a/src/Component/Analytics/Facet/Pivot.php b/src/Component/Analytics/Facet/Pivot.php
index 5d5048e8a..c73fc44bb 100644
--- a/src/Component/Analytics/Facet/Pivot.php
+++ b/src/Component/Analytics/Facet/Pivot.php
@@ -93,8 +93,7 @@ public function setSort(Sort|array|null $sort): self
     /**
      * {@inheritdoc}
      */
-    #[\ReturnTypeWillChange]
-    public function jsonSerialize()
+    public function jsonSerialize(): mixed
     {
         return array_filter([
             'name' => $this->name,
diff --git a/src/Component/Analytics/Facet/PivotFacet.php b/src/Component/Analytics/Facet/PivotFacet.php
index 7fc349043..8fc13d790 100644
--- a/src/Component/Analytics/Facet/PivotFacet.php
+++ b/src/Component/Analytics/Facet/PivotFacet.php
@@ -70,8 +70,7 @@ public function addPivot(Pivot $pivot): self
     /**
      * {@inheritdoc}
      */
-    #[\ReturnTypeWillChange]
-    public function jsonSerialize()
+    public function jsonSerialize(): mixed
     {
         return array_filter([
             'type' => $this->getType(),
diff --git a/src/Component/Analytics/Facet/QueryFacet.php b/src/Component/Analytics/Facet/QueryFacet.php
index b8b60ebe6..bebaef1a5 100644
--- a/src/Component/Analytics/Facet/QueryFacet.php
+++ b/src/Component/Analytics/Facet/QueryFacet.php
@@ -66,8 +66,7 @@ public function addQuery(string $key, string $query): self
     /**
      * {@inheritdoc}
      */
-    #[\ReturnTypeWillChange]
-    public function jsonSerialize()
+    public function jsonSerialize(): mixed
     {
         return array_filter([
             'type' => $this->getType(),
diff --git a/src/Component/Analytics/Facet/RangeFacet.php b/src/Component/Analytics/Facet/RangeFacet.php
index a28bfbb76..197137744 100644
--- a/src/Component/Analytics/Facet/RangeFacet.php
+++ b/src/Component/Analytics/Facet/RangeFacet.php
@@ -258,8 +258,7 @@ public function setOthers(array $others): self
     /**
      * {@inheritdoc}
      */
-    #[\ReturnTypeWillChange]
-    public function jsonSerialize()
+    public function jsonSerialize(): mixed
     {
         return array_filter(
             [
diff --git a/src/Component/Analytics/Facet/Sort/Criterion.php b/src/Component/Analytics/Facet/Sort/Criterion.php
index 47e28aa8e..692f72e13 100644
--- a/src/Component/Analytics/Facet/Sort/Criterion.php
+++ b/src/Component/Analytics/Facet/Sort/Criterion.php
@@ -112,8 +112,7 @@ public function setDirection(string $direction): self
     /**
      * {@inheritdoc}
      */
-    #[\ReturnTypeWillChange]
-    public function jsonSerialize()
+    public function jsonSerialize(): mixed
     {
         return array_filter([
             'type' => $this->type,
diff --git a/src/Component/Analytics/Facet/Sort/Sort.php b/src/Component/Analytics/Facet/Sort/Sort.php
index dfdf6032e..45f38d21a 100644
--- a/src/Component/Analytics/Facet/Sort/Sort.php
+++ b/src/Component/Analytics/Facet/Sort/Sort.php
@@ -111,8 +111,7 @@ public function setOffset(?int $offset): self
     /**
      * {@inheritdoc}
      */
-    #[\ReturnTypeWillChange]
-    public function jsonSerialize()
+    public function jsonSerialize(): mixed
     {
         return array_filter([
             'limit' => $this->limit,
diff --git a/src/Component/Analytics/Facet/ValueFacet.php b/src/Component/Analytics/Facet/ValueFacet.php
index 2def20498..bdf977ff1 100644
--- a/src/Component/Analytics/Facet/ValueFacet.php
+++ b/src/Component/Analytics/Facet/ValueFacet.php
@@ -77,8 +77,7 @@ public function setSort(Sort|array|null $sort): self
     /**
      * {@inheritdoc}
      */
-    #[\ReturnTypeWillChange]
-    public function jsonSerialize()
+    public function jsonSerialize(): mixed
     {
         return array_filter([
             'type' => $this->getType(),
diff --git a/src/Component/Analytics/Grouping.php b/src/Component/Analytics/Grouping.php
index 6ae759b30..1bf4180c3 100644
--- a/src/Component/Analytics/Grouping.php
+++ b/src/Component/Analytics/Grouping.php
@@ -132,8 +132,7 @@ public function addFacet(AbstractFacet $facet): self
     /**
      * {@inheritdoc}
      */
-    #[\ReturnTypeWillChange]
-    public function jsonSerialize()
+    public function jsonSerialize(): mixed
     {
         return array_filter([
             'expressions' => $this->expressions,
diff --git a/src/Core/Query/AbstractDocument.php b/src/Core/Query/AbstractDocument.php
index 0bfd3c9d8..2cfc776ea 100644
--- a/src/Core/Query/AbstractDocument.php
+++ b/src/Core/Query/AbstractDocument.php
@@ -133,9 +133,6 @@ public function offsetGet($offset)
 
     /**
      * {@inheritdoc}
-     *
-     * @return mixed
      */
-    #[\ReturnTypeWillChange]
-    abstract public function jsonSerialize();
+    abstract public function jsonSerialize(): mixed;
 }
diff --git a/src/Core/Query/Result/Result.php b/src/Core/Query/Result/Result.php
index bebd6a53b..ea6d8c810 100644
--- a/src/Core/Query/Result/Result.php
+++ b/src/Core/Query/Result/Result.php
@@ -132,8 +132,7 @@ public function getData(): array
     /**
      * {@inheritdoc}
      */
-    #[\ReturnTypeWillChange]
-    public function jsonSerialize()
+    public function jsonSerialize(): mixed
     {
         return $this->getData();
     }
diff --git a/src/Plugin/MinimumScoreFilter/Document.php b/src/Plugin/MinimumScoreFilter/Document.php
index 93b24b625..b7eeebaed 100644
--- a/src/Plugin/MinimumScoreFilter/Document.php
+++ b/src/Plugin/MinimumScoreFilter/Document.php
@@ -186,8 +186,7 @@ public function getFields(): array
     /**
      * {@inheritdoc}
      */
-    #[\ReturnTypeWillChange]
-    public function jsonSerialize()
+    public function jsonSerialize(): mixed
     {
         return $this->document;
     }
diff --git a/src/QueryType/Select/Result/Document.php b/src/QueryType/Select/Result/Document.php
index 7445d7336..e8bec7de1 100644
--- a/src/QueryType/Select/Result/Document.php
+++ b/src/QueryType/Select/Result/Document.php
@@ -54,8 +54,7 @@ public function __set(string $name, mixed $value): void
     /**
      * {@inheritdoc}
      */
-    #[\ReturnTypeWillChange]
-    public function jsonSerialize()
+    public function jsonSerialize(): mixed
     {
         return $this->getFields();
     }
diff --git a/src/QueryType/Update/Query/Document.php b/src/QueryType/Update/Query/Document.php
index 7317aa478..0e1855d50 100644
--- a/src/QueryType/Update/Query/Document.php
+++ b/src/QueryType/Update/Query/Document.php
@@ -460,8 +460,7 @@ public function getVersion(): ?int
     /**
      * {@inheritdoc}
      */
-    #[\ReturnTypeWillChange]
-    public function jsonSerialize()
+    public function jsonSerialize(): mixed
     {
         $fields = $this->getFields();