diff --git a/trunk/doc/CHANGELOG.md b/trunk/doc/CHANGELOG.md
index 6122b2121..1e9877d94 100644
--- a/trunk/doc/CHANGELOG.md
+++ b/trunk/doc/CHANGELOG.md
@@ -7,6 +7,7 @@ The changelog for SRS.
 <a name="v6-changes"></a>
 
 ## SRS 6.0 Changelog
+* v6.0, 2025-09-20, Fix WHIP with transcoding bug. v6.0.178 (#4495)
 * v6.0, 2025-09-15, RTC2RTMP: Fix sequence number wraparound assertion crashes. v6.0.177 (#4491)
 * v6.0, 2025-09-05, RTX: Fix race condition for timer. v6.0.176 (#4470) (#4474)
 * v6.0, 2025-08-26, Merge [#4451](https://github.com/ossrs/srs/pull/4451): RTC: Fix null pointer crash in RTC2RTMP when start packet is missing. v6.0.175 (#4451)
diff --git a/trunk/src/app/srs_app_rtc_source.cpp b/trunk/src/app/srs_app_rtc_source.cpp
index 229ca049f..cb05232c2 100644
--- a/trunk/src/app/srs_app_rtc_source.cpp
+++ b/trunk/src/app/srs_app_rtc_source.cpp
@@ -541,6 +541,10 @@ void SrsRtcSource::set_bridge(ISrsStreamBridge* bridge)
     srs_freep(bridge_);
     bridge_ = bridge;
 
+    if (!bridge) {
+        return;
+    }
+
 #ifdef SRS_FFMPEG_FIT
     srs_freep(frame_builder_);
     frame_builder_ = new SrsRtcFrameBuilder(bridge);
@@ -626,11 +630,11 @@ srs_error_t SrsRtcSource::on_publish()
     // If bridge to other source, handle event and start timer to request PLI.
     if (bridge_) {
 #ifdef SRS_FFMPEG_FIT
-        if ((err = frame_builder_->initialize(req)) != srs_success) {
+        if (frame_builder_ && (err = frame_builder_->initialize(req)) != srs_success) {
             return srs_error_wrap(err, "frame builder initialize");
         }
 
-        if ((err = frame_builder_->on_publish()) != srs_success) {
+        if (frame_builder_ && (err = frame_builder_->on_publish()) != srs_success) {
             return srs_error_wrap(err, "frame builder on publish");
         }
 #endif
@@ -680,8 +684,10 @@ void SrsRtcSource::on_unpublish()
         _srs_hybrid->timer100ms()->unsubscribe(this);
 
 #ifdef SRS_FFMPEG_FIT
-        frame_builder_->on_unpublish();
-        srs_freep(frame_builder_);
+        if (frame_builder_) {
+            frame_builder_->on_unpublish();
+            srs_freep(frame_builder_);
+        }
 #endif
 
         bridge_->on_unpublish();
diff --git a/trunk/src/core/srs_core_version6.hpp b/trunk/src/core/srs_core_version6.hpp
index a47cbcd67..e81210619 100644
--- a/trunk/src/core/srs_core_version6.hpp
+++ b/trunk/src/core/srs_core_version6.hpp
@@ -9,6 +9,6 @@
 
 #define VERSION_MAJOR 6
 #define VERSION_MINOR 0
-#define VERSION_REVISION 177
+#define VERSION_REVISION 178
 
 #endif