diff --git a/indra/llcommon/workqueue.cpp b/indra/llcommon/workqueue.cpp
index 0407d6c3e9..111ad4322e 100644
--- a/indra/llcommon/workqueue.cpp
+++ b/indra/llcommon/workqueue.cpp
@@ -38,7 +38,8 @@ LL::WorkQueueBase::WorkQueueBase(const std::string& name, bool auto_shutdown)
     {
         // Register for "LLApp" events so we can implicitly close() on viewer shutdown
         std::string listener_name = "WorkQueue:" + getKey();
-        LLEventPumps::instance().obtain("LLApp").listen(
+        LLEventPumps* pump = LLEventPumps::getInstance();
+        pump->obtain("LLApp").listen(
             listener_name,
             [this](const LLSD& stat)
             {
@@ -54,14 +55,25 @@ LL::WorkQueueBase::WorkQueueBase(const std::string& name, bool auto_shutdown)
 
         // Store the listener name so we can unregister in the destructor
         mListenerName = listener_name;
+        mPumpHandle = pump->getHandle();
     }
 }
 
 LL::WorkQueueBase::~WorkQueueBase()
 {
-    if (!mListenerName.empty() && !LLEventPumps::wasDeleted())
+    if (!mListenerName.empty() && !mPumpHandle.isDead())
     {
-        LLEventPumps::instance().obtain("LLApp").stopListening(mListenerName);
+        // Due to shutdown order issues, use handle, not a singleton
+        // and ignore fiber issue.
+        try
+        {
+            LLEventPumps* pump = mPumpHandle.get();
+            pump->obtain("LLApp").stopListening(mListenerName);
+        }
+        catch (const boost::fibers::lock_error&)
+        {
+            // Likely mutex is down, ignore
+        }
     }
 }
 
diff --git a/indra/llcommon/workqueue.h b/indra/llcommon/workqueue.h
index 573203a5b3..69f3286c1b 100644
--- a/indra/llcommon/workqueue.h
+++ b/indra/llcommon/workqueue.h
@@ -14,6 +14,7 @@
 
 #include "llcoros.h"
 #include "llexception.h"
+#include "llhandle.h"
 #include "llinstancetracker.h"
 #include "llinstancetrackersubclass.h"
 #include "threadsafeschedule.h"
@@ -22,6 +23,9 @@
 #include <functional>               // std::function
 #include <string>
 
+class LLEventPumps;
+
+
 namespace LL
 {
 
@@ -202,6 +206,8 @@ namespace LL
 
         // Name used for the LLApp event listener (empty if not registered)
         std::string mListenerName;
+        // Due to shutdown order issues, store by handle
+        LLHandle<LLEventPumps> mPumpHandle;
     };
 
 /*****************************************************************************
diff --git a/indra/newview/llappviewer.cpp b/indra/newview/llappviewer.cpp
index 27995288e5..e5fbd06f69 100644
--- a/indra/newview/llappviewer.cpp
+++ b/indra/newview/llappviewer.cpp
@@ -388,7 +388,15 @@ const std::string LOGOUT_MARKER_FILE_NAME("SecondLife.logout_marker");
 static std::string gLaunchFileOnQuit;
 
 // Used on Win32 for other apps to identify our window (eg, win_setup)
+#if LL_VELOPACK
+// Velopack is deliberately different fron NSIS to not prevent nsis uninstall
+const char* const VIEWER_WINDOW_CLASSNAME = "Second\u00A0Life"; // no break space
+#else
+// NSIS relies on this to detect if viewer is up.
+// NSIS's method is somewhat unreliable since window
+// can close long before cleanup is done
 const char* const VIEWER_WINDOW_CLASSNAME = "Second Life";
+#endif
 
 //----------------------------------------------------------------------------
 
diff --git a/indra/newview/llappviewerwin32.cpp b/indra/newview/llappviewerwin32.cpp
index a02311b74c..0aa2ae5023 100644
--- a/indra/newview/llappviewerwin32.cpp
+++ b/indra/newview/llappviewerwin32.cpp
@@ -435,6 +435,20 @@ int APIENTRY WINMAIN(HINSTANCE hInstance,
     if (!velopack_initialize())
     {
         // Velopack handled the invocation (install/uninstall hook)
+
+        // Drop install related settings
+        gDirUtilp->initAppDirs("SecondLife");
+
+        std::string user_settings_path = gDirUtilp->getExpandedFilename(LL_PATH_USER_SETTINGS, "settings.xml");
+        LLControlGroup settings("global");
+        if (settings.loadFromFile(user_settings_path))
+        {
+            if (settings.controlExists("LastInstallVersion"))
+            {
+                settings.setString("LastInstallVersion", std::string());
+            }
+            settings.saveToFile(user_settings_path, true);
+        }
         return 0;
     }
 #endif
diff --git a/indra/newview/llstartup.cpp b/indra/newview/llstartup.cpp
index 6f0c9c99df..d9de8ca1ca 100644
--- a/indra/newview/llstartup.cpp
+++ b/indra/newview/llstartup.cpp
@@ -2619,18 +2619,25 @@ void release_notes_coro(const std::string url)
 void uninstall_nsis_if_required()
 {
 #if LL_VELOPACK && LL_WINDOWS
-    // Todo: perhaps use marker files?
-    // Debug variable isn't specific to one channel
-    // and something channel specific is needed.
     std::string last_install_ver = gSavedSettings.getString("LastInstallVersion");
-    LLVersionInfo* ver_inst = LLVersionInfo::getInstance();
-    if (ver_inst->getChannelAndVersion() == last_install_ver)
+    if (!last_install_ver.empty())
     {
         return;
     }
+    LLVersionInfo* ver_inst = LLVersionInfo::getInstance();
     gSavedSettings.setString("LastInstallVersion",
         ver_inst->getChannelAndVersion());
 
+    if (LLNotifications::instance().getIgnored("PromptRemoveNsisInstallation"))
+    {
+        // By default 'ignore' returns default button, which is uninstall
+        // for PromptRemoveNsisInstallation, but while we want the button
+        // to be the default, we don't want a scary UAC without a notice
+        // as a default action, so if this notification is ignored,
+        // we will treat it as if user is going to cancel the uninstall.
+        return;
+    }
+
     LL_INFOS() << "Looking for previous NSIS installs" << LL_ENDL;
 
     wchar_t buffer[MAX_PATH];
diff --git a/indra/newview/skins/default/xui/en/notifications.xml b/indra/newview/skins/default/xui/en/notifications.xml
index 26ed49dfac..f282e934ff 100644
--- a/indra/newview/skins/default/xui/en/notifications.xml
+++ b/indra/newview/skins/default/xui/en/notifications.xml
@@ -209,7 +209,8 @@ No tutorial is currently available.
 The uninstaller may display additional prompts requesting permission to access or modify files on your disk.
       <tag>confirm</tag>
     <usetemplate
-     name="okcancelbuttons"
+     ignoretext="Ask to remove legacy installation"
+     name="okcancelignore"
      notext="Cancel"
      yestext="Uninstall"/>
   </notification>