diff --git a/README.md b/README.md
index c9fc999df..eb2ebc961 100755
--- a/README.md
+++ b/README.md
@@ -403,6 +403,7 @@ Remark:
 =======
 ## History
 
+* v2.0, 2016-09-01, workaround [bug #511] the fly stfd in close. 2.0.211
 * v2.0, 2016-08-30, comment the pcr.
 * v2.0, 2016-08-18, fix [srs-librtmp#4](https://github.com/ossrs/srs-librtmp/issues/4) filter frame.
 * v2.0, 2016-08-10, fix socket timeout for librtmp.
@@ -1312,6 +1313,7 @@ Winlin
 [bug #546]: https://github.com/ossrs/srs/issues/546
 [bug #418]: https://github.com/ossrs/srs/issues/418
 [bug #509]: https://github.com/ossrs/srs/issues/509
+[bug #511]: https://github.com/ossrs/srs/issues/511
 [bug #xxxxxxxxxx]: https://github.com/ossrs/srs/issues/xxxxxxxxxx
 
 [exo #828]: https://github.com/google/ExoPlayer/pull/828
diff --git a/trunk/src/app/srs_app_rtmp_conn.cpp b/trunk/src/app/srs_app_rtmp_conn.cpp
index c4a2bef1b..1b1dcc0b9 100644
--- a/trunk/src/app/srs_app_rtmp_conn.cpp
+++ b/trunk/src/app/srs_app_rtmp_conn.cpp
@@ -479,8 +479,11 @@ int SrsRtmpConn::on_reload_vhost_removed(string vhost)
     // if the vhost connected is removed, disconnect the client.
     srs_trace("vhost %s removed/disabled, close client url=%s", 
         vhost.c_str(), req->get_stream_url().c_str());
-        
-    srs_close_stfd(stfd);
+    
+    // should never close the fd in another thread,
+    // one fd should managed by one thread, we should use interrupt instead.
+    // so we just ignore the vhost enabled event.
+    //srs_close_stfd(stfd);
     
     return ret;
 }
diff --git a/trunk/src/app/srs_app_st.cpp b/trunk/src/app/srs_app_st.cpp
index cc095fa7a..ab36243a1 100644
--- a/trunk/src/app/srs_app_st.cpp
+++ b/trunk/src/app/srs_app_st.cpp
@@ -564,13 +564,9 @@ int srs_st_init()
 void srs_close_stfd(st_netfd_t& stfd)
 {
     if (stfd) {
-        int fd = st_netfd_fileno(stfd);
-        st_netfd_close(stfd);
-        stfd = NULL;
-        
-        // st does not close it sometimes, 
-        // close it manually.
-        close(fd);
+        // we must ensure the close is ok.
+        int err = st_netfd_close(stfd);
+        srs_assert(err != -1);
     }
 }
 
diff --git a/trunk/src/app/srs_app_st.hpp b/trunk/src/app/srs_app_st.hpp
index 82e9d3f22..480c6b0c5 100644
--- a/trunk/src/app/srs_app_st.hpp
+++ b/trunk/src/app/srs_app_st.hpp
@@ -254,6 +254,7 @@ public:
 extern int srs_st_init();
 
 // close the netfd, and close the underlayer fd.
+// @remark when close, user must ensure io completed.
 extern void srs_close_stfd(st_netfd_t& stfd);
 
 #endif
diff --git a/trunk/src/core/srs_core.hpp b/trunk/src/core/srs_core.hpp
index c4ca91f57..bf8c4faa4 100644
--- a/trunk/src/core/srs_core.hpp
+++ b/trunk/src/core/srs_core.hpp
@@ -31,7 +31,7 @@ CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 // current release version
 #define VERSION_MAJOR       3
 #define VERSION_MINOR       0
-#define VERSION_REVISION    210
+#define VERSION_REVISION    211
 
 // generated by configure, only macros.
 #include <srs_auto_headers.hpp>