diff --git a/src/Jaeger/Jaeger.php b/src/Jaeger/Jaeger.php
index 72f2b46..9ba943c 100644
--- a/src/Jaeger/Jaeger.php
+++ b/src/Jaeger/Jaeger.php
@@ -16,6 +16,7 @@
 namespace Jaeger;
 
 use Jaeger\Sampler\Sampler;
+use OpenTracing\Exceptions\UnsupportedFormat;
 use OpenTracing\SpanContext;
 use OpenTracing\Formats;
 use OpenTracing\Tracer;
@@ -44,6 +45,7 @@ class Jaeger implements Tracer{
 
     public $processThrift = '';
 
+    /** @var Propagator|null */
     public $propagator = null;
 
     public function __construct($serverName = '', Reporter $reporter, Sampler $sampler,
@@ -136,7 +138,7 @@ public function inject(SpanContext $spanContext, $format, &$carrier){
         if($format == Formats\TEXT_MAP){
             $this->propagator->inject($spanContext, $format, $carrier);
         }else{
-            throw new \Exception("not support format $format");
+            throw UnsupportedFormat::forFormat($format);
         }
     }
 
@@ -150,7 +152,7 @@ public function extract($format, $carrier){
         if($format == Formats\TEXT_MAP){
             return $this->propagator->extract($format, $carrier);
         }else{
-            throw new \Exception("not support format $format");
+            throw UnsupportedFormat::forFormat($format);
         }
     }
 
diff --git a/src/Jaeger/Propagator/JaegerPropagator.php b/src/Jaeger/Propagator/JaegerPropagator.php
index 9290b31..763435f 100644
--- a/src/Jaeger/Propagator/JaegerPropagator.php
+++ b/src/Jaeger/Propagator/JaegerPropagator.php
@@ -30,17 +30,23 @@ public function inject(SpanContext $spanContext, $format, &$carrier){
     }
 
 
-    /**
-     * 提取
-     * @param string $format
-     * @param $carrier
-     */
     public function extract($format, $carrier){
-        $spanContext = new SpanContext(0, 0, 0, null, 0);
-
+        $spanContext = null;
+        
         $carrier = array_change_key_case($carrier, CASE_LOWER);
 
         foreach ($carrier as $k => $v){
+            
+            if(!in_array($k, [Constants\Tracer_State_Header_Name,
+                Constants\Jaeger_Debug_Header, Constants\Jaeger_Baggage_Header]) &&
+                stripos($k, Constants\Trace_Baggage_Header_Prefix) === false){
+                continue;
+            }
+
+            if($spanContext === null){
+                $spanContext = new SpanContext(0, 0, 0, null, 0);
+            }
+            
             if(is_array($v)){
                 $v = urldecode(current($v));
             }else {
diff --git a/src/Jaeger/Propagator/Propagator.php b/src/Jaeger/Propagator/Propagator.php
index b3cc10c..d094e4d 100644
--- a/src/Jaeger/Propagator/Propagator.php
+++ b/src/Jaeger/Propagator/Propagator.php
@@ -32,7 +32,8 @@ public function inject(SpanContext $spanContext, $format, &$carrier);
      * 提取
      * @param string $format
      * @param $carrier
+     * @return SpanContext|null
      */
     public function extract($format, $carrier);
 
-}
\ No newline at end of file
+}
diff --git a/src/Jaeger/Propagator/ZipkinPropagator.php b/src/Jaeger/Propagator/ZipkinPropagator.php
index 41f2f0d..7dfcb41 100644
--- a/src/Jaeger/Propagator/ZipkinPropagator.php
+++ b/src/Jaeger/Propagator/ZipkinPropagator.php
@@ -29,7 +29,19 @@ public function inject(SpanContext $spanContext, $format, &$carrier){
 
 
     public function extract($format, $carrier){
-        $spanContext = new SpanContext(0, 0, 0, null, 0);
+        $spanContext = null;
+
+        foreach ($carrier as $k => $val) {
+            if (in_array($k, [Constants\X_B3_TRACEID,
+                Constants\X_B3_PARENT_SPANID, Constants\X_B3_SPANID, Constants\X_B3_SAMPLED])
+            ) {
+                if($spanContext === null){
+                    $spanContext = new SpanContext(0, 0, 0, null, 0);
+                }
+                continue;
+            }
+        }
+        
         if(isset($carrier[Constants\X_B3_TRACEID]) && $carrier[Constants\X_B3_TRACEID]){
             $spanContext->traceIdToString($carrier[Constants\X_B3_TRACEID]);
         }
@@ -49,4 +61,4 @@ public function extract($format, $carrier){
 
         return $spanContext;
     }
-}
\ No newline at end of file
+}
diff --git a/tests/JaegerTest.php b/tests/JaegerTest.php
index 0bbcff4..df7578e 100644
--- a/tests/JaegerTest.php
+++ b/tests/JaegerTest.php
@@ -82,7 +82,7 @@ public function testInjectUnSupportFormat(){
         $Jaeger->setPropagator(new JaegerPropagator());
 
         $context = new SpanContext(1, 1, 1, null, 1);
-        $this->expectExceptionMessage('not support format http_headers');
+        $this->expectExceptionMessage('The format \'http_headers\' is not supported.');
 
         $Jaeger->inject($context, Formats\HTTP_HEADERS, $_SERVER);
     }
@@ -106,7 +106,7 @@ public function testExtractUnSupportFormat(){
         $Jaeger->setPropagator(new JaegerPropagator());
 
         $_SERVER[strtoupper(Constants\Tracer_State_Header_Name)] = '1:1:1:1';
-        $this->expectExceptionMessage('not support format http_headers');
+        $this->expectExceptionMessage('The format \'http_headers\' is not supported.');
 
         $Jaeger->extract(Formats\HTTP_HEADERS, $_SERVER);
     }
@@ -217,4 +217,4 @@ public function testNestedSpanBaggage(){
 
         $this->assertEquals($parent->getBaggageItem('key'), $child->getBaggageItem('key'));
     }
-}
\ No newline at end of file
+}
diff --git a/tests/Propagator/JaegerPropagatorTest.php b/tests/Propagator/JaegerPropagatorTest.php
index 832b770..937a4e7 100644
--- a/tests/Propagator/JaegerPropagatorTest.php
+++ b/tests/Propagator/JaegerPropagatorTest.php
@@ -70,7 +70,7 @@ public function testExtract(){
     public function testExtractDebugId(){
 
         $jaeger = new JaegerPropagator();
-        $carrier = [];
+        $carrier[Constants\Trace_Baggage_Header_Prefix . 'baggage'] = 2;
 
         $context = $jaeger->extract(Formats\TEXT_MAP, $carrier);
         $this->assertTrue($context->debugId == 0);
@@ -85,6 +85,7 @@ public function testExtractUberctx(){
         $jaeger = new JaegerPropagator();
 
         $carrier[Constants\Trace_Baggage_Header_Prefix] = '2.0.0';
+        $carrier[Constants\Jaeger_Debug_Header] = true;
         $context = $jaeger->extract(Formats\TEXT_MAP, $carrier);
         $this->assertTrue($context->baggage == null);
 
@@ -113,6 +114,7 @@ public function testExtractBadBaggageHeader(){
         $carrier = [];
 
         $carrier[Constants\Jaeger_Baggage_Header] = 'version';
+        $carrier[Constants\Jaeger_Debug_Header] = true;
         $context = $jaeger->extract(Formats\TEXT_MAP, $carrier);
         $this->assertTrue($context->baggage == null);
     }
@@ -146,4 +148,13 @@ public function testExtractPsr7(){
         $this->assertTrue($context->spanId == 1562237095801441413);
         $this->assertTrue($context->flags == 1);
     }
-}
\ No newline at end of file
+
+
+    public function testExtractReturnsNull(){
+        $jaeger = new JaegerPropagator();
+        $carrier = [];
+
+        $context = $jaeger->extract(Formats\TEXT_MAP, $carrier);
+        $this->assertNull($context);
+    }
+}
diff --git a/tests/Propagator/ZipkinPropagatorTest.php b/tests/Propagator/ZipkinPropagatorTest.php
index 40ef581..94a3c28 100644
--- a/tests/Propagator/ZipkinPropagatorTest.php
+++ b/tests/Propagator/ZipkinPropagatorTest.php
@@ -92,4 +92,13 @@ public function testExtract128Bit(){
         $this->assertTrue($context->spanId == 1562289663898779811);
         $this->assertTrue($context->flags == 1);
     }
-}
\ No newline at end of file
+
+
+    public function testExtractReturnsNull(){
+        $jaeger = new ZipkinPropagator();
+        $carrier = [];
+
+        $context = $jaeger->extract(Formats\TEXT_MAP, $carrier);
+        $this->assertNull($context);
+    }
+}