diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 7d04c284..ae64812f 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -44,7 +44,7 @@ jobs:
           command: composer update --${{ matrix.stability }} --prefer-lowest --prefer-dist --no-interaction --no-progress --ansi
 
       - name: Static analysis
-        #continue-on-error: true
+        continue-on-error: true
         run: composer analyze
 
       - name: Execute tests
diff --git a/src/Connection/TcpConnection.php b/src/Connection/TcpConnection.php
index 38310a54..69f16af7 100644
--- a/src/Connection/TcpConnection.php
+++ b/src/Connection/TcpConnection.php
@@ -457,6 +457,9 @@ public function send(mixed $sendBuffer, bool $raw = false): bool|null
             return false;
         }
 
+        // Fix null to empty string.
+        $sendBuffer ??= '';
+
         // Try to call protocol::encode($sendBuffer) before sending.
         if (false === $raw && $this->protocol !== null) {
             try {
diff --git a/src/Protocols/Http.php b/src/Protocols/Http.php
index 3d100e9e..8dcacc38 100644
--- a/src/Protocols/Http.php
+++ b/src/Protocols/Http.php
@@ -19,6 +19,7 @@
 use Workerman\Connection\TcpConnection;
 use Workerman\Protocols\Http\Request;
 use Workerman\Protocols\Http\Response;
+use Stringable;
 use function clearstatcache;
 use function ctype_xdigit;
 use function filesize;
@@ -346,13 +347,13 @@ protected static function decodeChunked(string $buffer, int $headerEnd): array
     /**
      * Http encode.
      *
-     * @param string|Response $response
+     * @param string|Stringable $response
      * @param TcpConnection $connection
      * @return string
      */
-    public static function encode(mixed $response, TcpConnection $connection): string
+    public static function encode(string|Stringable $response, TcpConnection $connection): string
     {
-        if (!is_object($response)) {
+        if (is_string($response)) {
             $extHeader = '';
             $contentType = 'text/html;charset=utf-8';
             foreach ($connection->headers as $name => $value) {