diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 4ecac00..717c8d1 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -42,7 +42,7 @@ jobs:
       # Cache packages
       - name: Cache Composer packages
         id: composer-cache
-        uses: actions/cache@v2
+        uses: actions/cache@v4
         with:
           path: vendor
           key: ${{ runner.os }}-php-${{ hashFiles('**/composer.lock') }}
diff --git a/src/EventPayloadBuilder.php b/src/EventPayloadBuilder.php
index 74d382a..99b6269 100644
--- a/src/EventPayloadBuilder.php
+++ b/src/EventPayloadBuilder.php
@@ -27,6 +27,19 @@ class EventPayloadBuilder
      */
     private $stacktraceFrameBuilder;
 
+    /**
+     * Allowed keys for stacktrace frames
+     */
+    private const ALLOWED_KEYS = [
+        'file',
+        'line',
+        'column',
+        'sourceCode',
+        'function',
+        'arguments',
+        'additionalData',
+    ];
+
     /**
      * EventPayloadFactory constructor.
      */
@@ -76,6 +89,12 @@ public function create(array $data): EventPayload
             $stacktrace = debug_backtrace();
         }
 
+        /**
+         * Normalize frames to BacktraceFrame shape and wrap extra fields in additionalData.
+         * Also sanitize keys for MongoDB compatibility.
+         */
+        $stacktrace = $this->normalizeBacktrace($stacktrace);
+
         if (isset($data['type'])) {
             $eventPayload->setType($data['type']);
         }
@@ -107,4 +126,136 @@ private function resolveAddons(): array
 
         return $result;
     }
+
+    /**
+     * Normalize any stacktrace representation to BacktraceFrame shape
+     * and wrap unknown fields into additionalData with safe keys
+     *
+     * @param array $stack
+     *
+     * @return array
+     */
+    private function normalizeBacktrace(array $stack): array
+    {
+        $normalized = [];
+
+        foreach ($stack as $frame) {
+            if (!is_array($frame)) {
+                continue;
+            }
+
+            $file = isset($frame['file']) ? (string) $frame['file'] : '';
+            $line = isset($frame['line']) ? (int) $frame['line'] : 0;
+            $functionName = null;
+
+            if (isset($frame['function'])) {
+                if (!empty($frame['class']) && !empty($frame['type'])) {
+                    $functionName = (string) $frame['class'] . (string) $frame['type'] . (string) $frame['function'];
+                } else {
+                    $functionName = (string) $frame['function'];
+                }
+            } elseif (isset($frame['functionName'])) {
+                $functionName = (string) $frame['functionName'];
+            }
+
+            $additional = [];
+            foreach ($frame as $key => $value) {
+                if (!in_array($key, self::ALLOWED_KEYS, true)) {
+                    // Drop heavy/unserializable objects from 'object' field; store class name instead
+                    if ($key === 'object') {
+                        $value = is_object($value) ? get_class($value) : $value;
+                    }
+
+                    $additional[$key] = $this->transformForJson($value);
+                }
+            }
+
+            $normalized[] = $this->sanitizeArrayKeys([
+                'file'          => $file,
+                'line'          => $line,
+                'column'        => null,
+                'sourceCode'    => isset($frame['sourceCode']) && is_array($frame['sourceCode']) ? $frame['sourceCode'] : null,
+                'function'      => $functionName,
+                // Keep arguments only if it already looks like desired string[]; otherwise omit
+                // Limit argument processing to first 10 items to avoid performance issues
+                'arguments'     => (isset($frame['arguments']) && is_array($frame['arguments'])) ? array_values(array_map('strval', array_slice($frame['arguments'], 0, 10))) : [],
+                'additionalData'=> $additional,
+            ]);
+        }
+
+        return $normalized;
+    }
+
+    /**
+     * Recursively sanitize array keys to be MongoDB-safe
+     * - replace dots with underscores
+     * - replace leading '$' with 'dollar_'
+     *
+     * @param mixed $value
+     *
+     * @return mixed
+     */
+    private function sanitizeArrayKeys($value)
+    {
+        if (!is_array($value)) {
+            return $value;
+        }
+
+        $sanitized = [];
+
+        foreach ($value as $key => $subValue) {
+            $newKey = $key;
+
+            if (is_string($newKey)) {
+                if (strpos($newKey, '.') !== false) {
+                    $newKey = str_replace('.', '_', $newKey);
+                }
+
+                if (isset($newKey[0]) && $newKey[0] === '$') {
+                    $newKey = 'dollar_' . substr($newKey, 1);
+                }
+            }
+
+            $sanitized[$newKey] = $this->sanitizeArrayKeys($subValue);
+        }
+
+        return $sanitized;
+    }
+
+    /**
+     * Transform values to JSON-serializable representation
+     *
+     * @param mixed $value
+     *
+     * @return mixed
+     */
+    private function transformForJson($value)
+    {
+        if (is_array($value)) {
+            $result = [];
+            foreach ($value as $k => $v) {
+                $result[$k] = $this->transformForJson($v);
+            }
+
+            return $result;
+        }
+
+        if (is_null($value)) {
+            return null;
+        }
+
+        if (is_callable($value)) {
+            return 'Closure';
+        }
+
+        if (is_object($value)) {
+            return get_class($value);
+        }
+
+        if (is_resource($value)) {
+            return 'Resource';
+        }
+
+        return $value;
+    }
 }