diff --git a/AUTHORS b/AUTHORS
index bd3e4bd..3c97237 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -33,6 +33,7 @@
 Matt Giuca <mgiuca@chromium.org>
 Michael Doppler <m.doppler@gmail.com>
 Miklos Vajna <vmiklos@vmiklos.hu>
+Minh Trần <myoki.crystal@gmail.com>
 Nico Weber <thakis@chromium.org>
 Nicolás Peña <npm@chromium.org>
 Peter Kasting <pkasting@chromium.org>
diff --git a/fpdfsdk/cpdfsdk_formfillenvironment.cpp b/fpdfsdk/cpdfsdk_formfillenvironment.cpp
old mode 100644
new mode 100755
index 9a5e726..81fd110
--- a/fpdfsdk/cpdfsdk_formfillenvironment.cpp
+++ b/fpdfsdk/cpdfsdk_formfillenvironment.cpp
@@ -669,6 +669,10 @@
   ObservedPtr<CPDFSDK_Annot> pLastFocusAnnot(m_pFocusAnnot.Get());
   if (!pAnnotHandler->Annot_OnChangeFocus(pAnnot, &pLastFocusAnnot))
     return false;
+
+  // |pAnnot| may be destroyed in |Annot_OnChangeFocus|.
+  if (!pAnnot->HasObservable())
+    return false;
 #endif  // PDF_ENABLE_XFA
   if (!pAnnotHandler->Annot_OnSetFocus(pAnnot, 0))
     return false;
diff --git a/fpdfsdk/cpdfsdk_xfawidgethandler.cpp b/fpdfsdk/cpdfsdk_xfawidgethandler.cpp
index bbecd7c..b6fc970 100644
--- a/fpdfsdk/cpdfsdk_xfawidgethandler.cpp
+++ b/fpdfsdk/cpdfsdk_xfawidgethandler.cpp
@@ -537,9 +537,14 @@
   if (!pXFAPageView)
     return true;
 
+  ObservedPtr<CXFA_FFPageView> pObservedXFAPageView(pXFAPageView);
   bool bRet = pXFAPageView->GetDocView()->SetFocus(hWidget);
-  if (pXFAPageView->GetDocView()->GetFocusWidget() == hWidget)
+
+  // Check |pXFAPageView| again because |SetFocus| can trigger JS to destroy it.
+  if (pObservedXFAPageView &&
+      pXFAPageView->GetDocView()->GetFocusWidget() == hWidget){
     bRet = true;
+  }
 
   return bRet;
 }
diff --git a/xfa/fxfa/cxfa_ffpageview.h b/xfa/fxfa/cxfa_ffpageview.h
old mode 100644
new mode 100755
index 768a3b9..d49c69c
--- a/xfa/fxfa/cxfa_ffpageview.h
+++ b/xfa/fxfa/cxfa_ffpageview.h
@@ -10,6 +10,7 @@
 #include <memory>
 #include <vector>
 
+#include "core/fxcrt/observed_ptr.h"
 #include "xfa/fxfa/layout/cxfa_contentlayoutitem.h"
 #include "xfa/fxfa/layout/cxfa_traversestrategy_layoutitem.h"
 #include "xfa/fxfa/layout/cxfa_viewlayoutitem.h"
@@ -17,7 +18,7 @@
 class CXFA_FFWidget;
 class CXFA_FFDocView;
 
-class CXFA_FFPageView {
+class CXFA_FFPageView : public Observable {
  public:
   CXFA_FFPageView(CXFA_FFDocView* pDocView, CXFA_Node* pPageArea);
   ~CXFA_FFPageView();