diff --git a/core/fpdfdoc/cpdf_aaction.cpp b/core/fpdfdoc/cpdf_aaction.cpp
index 8d95469..9a95340 100644
--- a/core/fpdfdoc/cpdf_aaction.cpp
+++ b/core/fpdfdoc/cpdf_aaction.cpp
@@ -32,9 +32,8 @@
     "DP",  // DocumentPrinted
 };
 
-// |g_sAATypes| should have one less element than enum AActionType due to
-// DocumentOpen, which is an artificial type.
-static_assert(FX_ArraySize(g_sAATypes) == CPDF_AAction::NumberOfActions - 1,
+// |g_sAATypes| should have as many elements as enum AActionType.
+static_assert(FX_ArraySize(g_sAATypes) == CPDF_AAction::NumberOfActions,
               "g_sAATypes count mismatch");
 
 }  // namespace
@@ -53,14 +52,3 @@
   return CPDF_Action(m_pDict ? m_pDict->GetDictFor(g_sAATypes[eType])
                              : nullptr);
 }
-
-// static
-bool CPDF_AAction::IsUserClick(AActionType eType) {
-  switch (eType) {
-    case ButtonUp:
-    case ButtonDown:
-      return true;
-    default:
-      return false;
-  }
-}
diff --git a/core/fpdfdoc/cpdf_aaction.h b/core/fpdfdoc/cpdf_aaction.h
index 90049f5..11eca01 100644
--- a/core/fpdfdoc/cpdf_aaction.h
+++ b/core/fpdfdoc/cpdf_aaction.h
@@ -35,7 +35,6 @@
     DocumentSaved,
     PrintDocument,
     DocumentPrinted,
-    DocumentOpen,
     NumberOfActions  // Must be last.
   };
 
@@ -47,8 +46,6 @@
   CPDF_Action GetAction(AActionType eType) const;
   const CPDF_Dictionary* GetDict() const { return m_pDict.Get(); }
 
-  static bool IsUserClick(AActionType eType);
-
  private:
   UnownedPtr<const CPDF_Dictionary> const m_pDict;
 };
diff --git a/fpdfsdk/cpdfsdk_actionhandler.cpp b/fpdfsdk/cpdfsdk_actionhandler.cpp
index f98585f..f951bfb 100644
--- a/fpdfsdk/cpdfsdk_actionhandler.cpp
+++ b/fpdfsdk/cpdfsdk_actionhandler.cpp
@@ -82,7 +82,7 @@
     CPDF_AAction::AActionType type,
     CPDFSDK_FormFillEnvironment* pFormFillEnv) {
   std::set<const CPDF_Dictionary*> visited;
-  return ExecuteBookMark(action, type, pFormFillEnv, pBookMark, &visited);
+  return ExecuteBookMark(action, pFormFillEnv, pBookMark, &visited);
 }
 
 bool CPDFSDK_ActionHandler::DoAction_Screen(
@@ -96,10 +96,9 @@
 
 bool CPDFSDK_ActionHandler::DoAction_Link(
     const CPDF_Action& action,
-    CPDF_AAction::AActionType type,
     CPDFSDK_FormFillEnvironment* pFormFillEnv) {
   std::set<const CPDF_Dictionary*> visited;
-  return ExecuteLinkAction(action, type, pFormFillEnv, &visited);
+  return ExecuteLinkAction(action, pFormFillEnv, &visited);
 }
 
 bool CPDFSDK_ActionHandler::DoAction_Field(
@@ -131,8 +130,7 @@
         RunDocumentOpenJavaScript(pFormFillEnv, L"", swJS);
     }
   } else {
-    DoAction_NoJs(action, CPDF_AAction::AActionType::DocumentOpen,
-                  pFormFillEnv);
+    DoAction_NoJs(action, pFormFillEnv);
   }
 
   for (int32_t i = 0, sz = action.GetSubActionsCount(); i < sz; i++) {
@@ -146,7 +144,6 @@
 
 bool CPDFSDK_ActionHandler::ExecuteLinkAction(
     const CPDF_Action& action,
-    CPDF_AAction::AActionType eType,
     CPDFSDK_FormFillEnvironment* pFormFillEnv,
     std::set<const CPDF_Dictionary*>* visited) {
   const CPDF_Dictionary* pDict = action.GetDict();
@@ -162,12 +159,12 @@
                          context->OnLink_MouseUp(pFormFillEnv);
                        });
   } else {
-    DoAction_NoJs(action, eType, pFormFillEnv);
+    DoAction_NoJs(action, pFormFillEnv);
   }
 
   for (int32_t i = 0, sz = action.GetSubActionsCount(); i < sz; i++) {
     CPDF_Action subaction = action.GetSubAction(i);
-    if (!ExecuteLinkAction(subaction, eType, pFormFillEnv, visited))
+    if (!ExecuteLinkAction(subaction, pFormFillEnv, visited))
       return false;
   }
 
@@ -193,7 +190,7 @@
         RunDocumentPageJavaScript(pFormFillEnv, type, swJS);
     }
   } else {
-    DoAction_NoJs(action, type, pFormFillEnv);
+    DoAction_NoJs(action, pFormFillEnv);
   }
 
   ASSERT(pFormFillEnv);
@@ -241,7 +238,7 @@
       }
     }
   } else {
-    DoAction_NoJs(action, type, pFormFillEnv);
+    DoAction_NoJs(action, pFormFillEnv);
   }
 
   for (int32_t i = 0, sz = action.GetSubActionsCount(); i < sz; i++) {
@@ -270,7 +267,7 @@
   if (action.GetType() == CPDF_Action::JavaScript)
     RunScriptForAction(action, pFormFillEnv, [](IJS_EventContext*) {});
   else
-    DoAction_NoJs(action, type, pFormFillEnv);
+    DoAction_NoJs(action, pFormFillEnv);
 
   for (int32_t i = 0, sz = action.GetSubActionsCount(); i < sz; i++) {
     CPDF_Action subaction = action.GetSubAction(i);
@@ -283,7 +280,6 @@
 
 bool CPDFSDK_ActionHandler::ExecuteBookMark(
     const CPDF_Action& action,
-    CPDF_AAction::AActionType type,
     CPDFSDK_FormFillEnvironment* pFormFillEnv,
     CPDF_Bookmark* pBookmark,
     std::set<const CPDF_Dictionary*>* visited) {
@@ -300,12 +296,12 @@
                          context->OnBookmark_MouseUp(pBookmark);
                        });
   } else {
-    DoAction_NoJs(action, type, pFormFillEnv);
+    DoAction_NoJs(action, pFormFillEnv);
   }
 
   for (int32_t i = 0, sz = action.GetSubActionsCount(); i < sz; i++) {
     CPDF_Action subaction = action.GetSubAction(i);
-    if (!ExecuteBookMark(subaction, type, pFormFillEnv, pBookmark, visited))
+    if (!ExecuteBookMark(subaction, pFormFillEnv, pBookmark, visited))
       return false;
   }
 
@@ -314,7 +310,6 @@
 
 void CPDFSDK_ActionHandler::DoAction_NoJs(
     const CPDF_Action& action,
-    CPDF_AAction::AActionType type,
     CPDFSDK_FormFillEnvironment* pFormFillEnv) {
   ASSERT(pFormFillEnv);
 
@@ -323,8 +318,7 @@
       DoAction_GoTo(pFormFillEnv, action);
       break;
     case CPDF_Action::URI:
-      if (CPDF_AAction::IsUserClick(type))
-        DoAction_URI(pFormFillEnv, action);
+      DoAction_URI(pFormFillEnv, action);
       break;
     case CPDF_Action::Hide:
       DoAction_Hide(action, pFormFillEnv);
@@ -333,8 +327,7 @@
       DoAction_Named(pFormFillEnv, action);
       break;
     case CPDF_Action::SubmitForm:
-      if (CPDF_AAction::IsUserClick(type))
-        DoAction_SubmitForm(action, pFormFillEnv);
+      DoAction_SubmitForm(action, pFormFillEnv);
       break;
     case CPDF_Action::ResetForm:
       DoAction_ResetForm(action, pFormFillEnv);
diff --git a/fpdfsdk/cpdfsdk_actionhandler.h b/fpdfsdk/cpdfsdk_actionhandler.h
index 94b347f..14cbc9c 100644
--- a/fpdfsdk/cpdfsdk_actionhandler.h
+++ b/fpdfsdk/cpdfsdk_actionhandler.h
@@ -44,7 +44,6 @@
                        CPDFSDK_FormFillEnvironment* pFormFillEnv,
                        CPDFSDK_Annot* pScreen);
   bool DoAction_Link(const CPDF_Action& action,
-                     CPDF_AAction::AActionType type,
                      CPDFSDK_FormFillEnvironment* pFormFillEnv);
   bool DoAction_Field(const CPDF_Action& action,
                       CPDF_AAction::AActionType type,
@@ -86,17 +85,14 @@
                            CPDFSDK_Annot* pScreen,
                            std::set<const CPDF_Dictionary*>* visited);
   bool ExecuteBookMark(const CPDF_Action& action,
-                       CPDF_AAction::AActionType type,
                        CPDFSDK_FormFillEnvironment* pFormFillEnv,
                        CPDF_Bookmark* pBookmark,
                        std::set<const CPDF_Dictionary*>* visited);
   bool ExecuteLinkAction(const CPDF_Action& action,
-                         CPDF_AAction::AActionType type,
                          CPDFSDK_FormFillEnvironment* pFormFillEnv,
                          std::set<const CPDF_Dictionary*>* visited);
 
   void DoAction_NoJs(const CPDF_Action& action,
-                     CPDF_AAction::AActionType type,
                      CPDFSDK_FormFillEnvironment* pFormFillEnv);
   void RunDocumentPageJavaScript(CPDFSDK_FormFillEnvironment* pFormFillEnv,
                                  CPDF_AAction::AActionType type,
diff --git a/fpdfsdk/cpdfsdk_widget.cpp b/fpdfsdk/cpdfsdk_widget.cpp
index 82776e3..8bd1f10 100644
--- a/fpdfsdk/cpdfsdk_widget.cpp
+++ b/fpdfsdk/cpdfsdk_widget.cpp
@@ -174,7 +174,6 @@
     case CPDF_AAction::PrintDocument:
     case CPDF_AAction::DocumentPrinted:
       break;
-    case CPDF_AAction::DocumentOpen:
     case CPDF_AAction::NumberOfActions:
       NOTREACHED();
       break;
diff --git a/fpdfsdk/fpdf_formfill_embeddertest.cpp b/fpdfsdk/fpdf_formfill_embeddertest.cpp
index 3e53753..8ff3a84 100644
--- a/fpdfsdk/fpdf_formfill_embeddertest.cpp
+++ b/fpdfsdk/fpdf_formfill_embeddertest.cpp
@@ -379,25 +379,6 @@
   UnloadPage(page);
 }
 
-class DoURIActionBlockedDelegate final : public EmbedderTest::Delegate {
- public:
-  void DoURIAction(FPDF_BYTESTRING uri) override {
-    FAIL() << "Navigated to " << uri;
-  }
-};
-
-TEST_F(FPDFFormFillEmbeddertest, BUG_851821) {
-  DoURIActionBlockedDelegate delegate;
-  SetDelegate(&delegate);
-
-  EXPECT_TRUE(OpenDocument("redirect.pdf"));
-  FPDF_PAGE page = LoadPage(0);
-  EXPECT_TRUE(page);
-  DoOpenActions();
-
-  UnloadPage(page);
-}
-
 #ifdef PDF_ENABLE_V8
 TEST_F(FPDFFormFillEmbeddertest, DisableJavaScript) {
   // Test that timers and intervals can't fire without JS.
diff --git a/testing/embedder_test.cpp b/testing/embedder_test.cpp
index 43f077c..215009c 100644
--- a/testing/embedder_test.cpp
+++ b/testing/embedder_test.cpp
@@ -241,8 +241,6 @@
   formfillinfo->FFI_SetTimer = SetTimerTrampoline;
   formfillinfo->FFI_KillTimer = KillTimerTrampoline;
   formfillinfo->FFI_GetPage = GetPageTrampoline;
-  formfillinfo->FFI_DoURIAction = DoURIActionTrampoline;
-
   if (javascript_option == JavaScriptOption::kEnableJavaScript)
     formfillinfo->m_pJsPlatform = platform;
 
@@ -480,13 +478,6 @@
 }
 
 // static
-void EmbedderTest::DoURIActionTrampoline(FPDF_FORMFILLINFO* info,
-                                         FPDF_BYTESTRING uri) {
-  EmbedderTest* test = static_cast<EmbedderTest*>(info);
-  return test->delegate_->DoURIAction(uri);
-}
-
-// static
 std::string EmbedderTest::HashBitmap(FPDF_BITMAP bitmap) {
   uint8_t digest[16];
   CRYPT_MD5Generate(static_cast<uint8_t*>(FPDFBitmap_GetBuffer(bitmap)),
diff --git a/testing/embedder_test.h b/testing/embedder_test.h
index a6a4cf5..6470763 100644
--- a/testing/embedder_test.h
+++ b/testing/embedder_test.h
@@ -62,9 +62,6 @@
     virtual FPDF_PAGE GetPage(FPDF_FORMFILLINFO* info,
                               FPDF_DOCUMENT document,
                               int page_index);
-
-    // Equivalent to FPDF_FORMFILLINFO::FFI_DoURIAction().
-    virtual void DoURIAction(FPDF_BYTESTRING uri) {}
   };
 
   EmbedderTest();
@@ -248,8 +245,6 @@
   static FPDF_PAGE GetPageTrampoline(FPDF_FORMFILLINFO* info,
                                      FPDF_DOCUMENT document,
                                      int page_index);
-  static void DoURIActionTrampoline(FPDF_FORMFILLINFO* info,
-                                    FPDF_BYTESTRING uri);
   static int WriteBlockCallback(FPDF_FILEWRITE* pFileWrite,
                                 const void* data,
                                 unsigned long size);
diff --git a/testing/resources/redirect.pdf b/testing/resources/redirect.pdf
deleted file mode 100644
index 2dcc23b..0000000
--- a/testing/resources/redirect.pdf
+++ /dev/null
@@ -1,22 +0,0 @@
-%PDF-1.7
-trailer
-<<
-/Root 1 0 R
->>
-1 0 obj
-<<
-/Type /Catalog
-/Pages 2 0 R
-/OpenAction 2 0 R
->>
-endobj
- 
-2 0 obj
-<<
-/Type /Action
-/S /URI
-/URI (http://evilzone.org) // URL HERE
->>
-endobj
- 
-%%EOF
\ No newline at end of file