diff --git a/Installer/HaxmSetup.nsi b/Installer/HaxmSetup.nsi
index 1250758f..f1e65aff 100644
--- a/Installer/HaxmSetup.nsi
+++ b/Installer/HaxmSetup.nsi
@@ -41,6 +41,7 @@ Unicode true
 !include 'UI.nsh'
 !include 'Utils.nsh'
 
+Var level
 Var code
 
 Section Main
@@ -58,6 +59,8 @@ Section Main
   File "assets\checktool.exe"
   ${Log} "Extract: checktool.exe... 100%"
 
+  StrCpy $level 0
+
 Check:
   Call CheckEnv
   Pop $0
@@ -66,18 +69,19 @@ Check:
     ${Case} ${ENV_STATUS_UNREADY}
       MessageBox MB_OK|MB_ICONEXCLAMATION "${DLG_WARNING}" /SD IDOK
       ${Log} "${DLG_WARNING}"
+      StrCpy $level ${EXIT_FLAG_WARNING}
       ${Break}
     ${Case} ${ENV_STATUS_INUSE}
       MessageBox MB_RETRYCANCEL|MB_ICONSTOP "${DLG_GUEST_ERROR}" /SD IDCANCEL \
           IDRETRY Check
       ${Log} "${DLG_GUEST_ERROR}"
-      ${Exit} 0 3
+      ${Exit} ${EXIT_MODE_NORMAL} ${EXIT_FLAG_ERROR}
       ${Break}
     ${Case} ${ENV_STATUS_UNSUPPORTED}
       MessageBox MB_OK|MB_ICONSTOP "${DLG_SYS_ERROR}" /SD IDOK
       ${Log} "${DLG_SYS_ERROR}"
       Call Restore
-      ${Exit} 0 3
+      ${Exit} ${EXIT_MODE_NORMAL} ${EXIT_FLAG_ERROR}
       ${Break}
     ${Default}
       ${Break}
@@ -91,6 +95,9 @@ Check:
   ${Log} "Create uninstaller: $INSTDIR\uninstall.exe"
 
   Call LoadDriver
+
+  IntOp $code $level | $code
+  ${Exit} ${EXIT_MODE_NORMAL} $code
 SectionEnd
 
 Function .onInit
@@ -127,18 +134,18 @@ Installed:
     ${Case} 0
       MessageBox MB_YESNO|MB_ICONQUESTION "${DLG_REINSTALL}" /SD IDYES IDYES \
           Reinstall
-      ${Exit} 1 0
+      ${Exit} ${EXIT_MODE_QUIT} 0
 Reinstall:
-      StrCpy $code 1
+      StrCpy $code ${EXIT_FLAG_REINSTALL}
       ${Log} "${LOG_REINSTALL}: $0"
       ${Break}
     ${Case} 1
       MessageBox MB_OK|MB_ICONEXCLAMATION "${DLG_DOWNGRADE}" /SD IDOK
       ${Log} "${LOG_UNINSTALL}: $0"
-      ${Exit} 1 3
+      ${Exit} ${EXIT_MODE_QUIT} ${EXIT_FLAG_ERROR}
       ${Break}
     ${Default}
-      StrCpy $code 2
+      StrCpy $code ${EXIT_FLAG_UPGRADE}
       ${Log} "${LOG_UPGRADE}: $0 => ${PRODUCT_VERSION}"
       ${Break}
   ${EndSwitch}
@@ -212,8 +219,6 @@ Function LoadDriver
 
   Call StartService
   Call CreateRegItems
-
-  ${Exit} 0 $code
 FunctionEnd
 
 Function onFinished
@@ -239,5 +244,5 @@ Function onFinished
 FunctionEnd
 
 Function onAbort
-  ${Exit} 0 0
+  ${Exit} ${EXIT_MODE_NORMAL} 0
 FunctionEnd
diff --git a/Installer/Resources.nsh b/Installer/Resources.nsh
index b6f7b49b..3c5926db 100644
--- a/Installer/Resources.nsh
+++ b/Installer/Resources.nsh
@@ -153,4 +153,16 @@
 !define ENV_STATUS_INUSE                    2
 !define ENV_STATUS_UNSUPPORTED              3
 
+# Exit code (%ERRORLEVEL%):
+#   Status levels
+!define EXIT_FLAG_WARNING          0x00000001
+!define EXIT_FLAG_ERROR            0x00000002
+#   Operation methods
+!define EXIT_FLAG_REINSTALL        0x00000010
+!define EXIT_FLAG_UPGRADE          0x00000020
+# Exit mode:
+!define EXIT_MODE_NORMAL                    0
+!define EXIT_MODE_QUIT                      1
+!define EXIT_MODE_ABORT                     2
+
 !endif  # RESOURCES_NSH_
diff --git a/Installer/Uninstall.nsi b/Installer/Uninstall.nsi
index f8d5d4c9..70270480 100644
--- a/Installer/Uninstall.nsi
+++ b/Installer/Uninstall.nsi
@@ -48,7 +48,7 @@ SectionEnd
 Function un.onInit
   MessageBox MB_YESNO|MB_ICONEXCLAMATION "${DLG_UNINSTALL}" /SD IDYES IDYES \
       Uninstall
-  ${Exit} 2 0
+  ${Exit} ${EXIT_MODE_ABORT} 0
 Uninstall:
 FunctionEnd
 
@@ -65,7 +65,7 @@ Check:
     MessageBox MB_RETRYCANCEL|MB_ICONSTOP "${DLG_GUEST_ERROR}" /SD IDCANCEL \
         IDRETRY Check
     ${Log} "${DLG_GUEST_ERROR}"
-    ${Exit} 1 3
+    ${Exit} ${EXIT_MODE_QUIT} ${EXIT_FLAG_ERROR}
   ${EndIf}
 
   ; Sometimes checktool.exe is still locked when removing $INSTDIR. Below two
@@ -84,7 +84,7 @@ Check:
 
   ${If} $1 == 1
     ${Log} "Error: Installed program files are being locked."
-    ${Exit} 0 3
+    ${Exit} ${EXIT_MODE_NORMAL} ${EXIT_FLAG_ERROR}
   ${EndIf}
 
 Remove:
@@ -99,5 +99,5 @@ Remove:
   ${Log} "Delete folder: $INSTDIR"
 
   SetAutoClose true
-  ${Exit} 0 0
+  ${Exit} ${EXIT_MODE_NORMAL} 0
 SectionEnd
diff --git a/Installer/Utils.nsh b/Installer/Utils.nsh
index 0f0d8dce..1fad9552 100644
--- a/Installer/Utils.nsh
+++ b/Installer/Utils.nsh
@@ -84,10 +84,10 @@
   ${CloseLog}
   SetErrorLevel ${Code}
   ${Switch} ${Mode}
-    ${Case} 1
+    ${Case} ${EXIT_MODE_QUIT}
       Quit
       ${Break}
-    ${Case} 2
+    ${Case} ${EXIT_MODE_ABORT}
       Abort
       ${Break}
     ${Default}
diff --git a/Installer/silent_install.bat b/Installer/silent_install.bat
index a65fa0ea..a7c849da 100644
--- a/Installer/silent_install.bat
+++ b/Installer/silent_install.bat
@@ -87,25 +87,36 @@ set timestamp=
     for /f "tokens=2 delims=-" %%i in ("%filename%") do set version=%%i
     call :log Start to install HAXM v%version%
     if exist %installer% %installer% /S
+    if %errorlevel% equ 5 (
+        :: Cancelled UAC confirmation dialog when not running as administrator
+        call :log User canceled
+        set exit_code=1
+        goto in_exit
+    )
     for %%i in (haxm_install-*.log) do set log=%%i
     call :log Log saved: %TEMP%\%log%
-    goto in_exit%errorlevel%
-:in_exit0
-    echo Intel HAXM installed successfully!
-    goto in_end
-:in_exit1
-    echo Intel HAXM reinstalled successfully!
-    goto in_end
-:in_exit2
-    echo Intel HAXM upgraded successfully!
-    goto in_end
-:in_exit3
-    echo Intel HAXM installation failed!
-    echo For more details, please check the installation log: %TEMP%\%log%
-    set exit_code=1
-    goto in_end
-:in_exit5
-:in_end
+    if %errorlevel% equ 2 (
+        echo Intel HAXM installation failed!
+        echo For more details, please check the installation log: %TEMP%\%log%
+        set exit_code=1
+        goto in_exit
+    )
+    set /a status="%errorlevel% & 0x0f"
+    set /a method="%errorlevel% & 0xf0"
+    if %method% equ 0 (
+        set installed=installed
+    ) else if %method% equ 0x10 (
+        set installed=reinstalled
+    ) else if %method% equ 0x20 (
+        set installed=upgraded
+    ) else goto in_exit
+    if %status% equ 0x01 (
+        echo Intel HAXM is %installed% but cannot be used until the system settings are ready.
+        echo For more details, please check the installation log: %TEMP%\%log%
+        goto in_exit
+    )
+    echo Intel HAXM %installed% successfully!
+:in_exit
     if exist %log% del /f %log%
     call :log End of installation
     exit /b %exit_code%
@@ -117,38 +128,40 @@ set timestamp=
     set uninstaller=%install_path%\uninstall.exe
     if not exist %uninstaller% (
         echo Intel HAXM is not installed.
-        goto un_end
+        call :log HAXM not found
+        goto un_exit
     )
     :: Run below command to check if running as administrator
-    net session >nul 2>&1 || goto un_exit1
+    net session >nul 2>&1 || goto un_fail
     :: Add _?= to execute uninstaller synchronously.
     :: By default, the uninstaller copies itself to the temporary directory and
     :: run asynchronously there.
     %uninstaller% /S _?=%ProgramFiles%\Intel\HAXM
     for %%i in (haxm_uninstall-*.log) do set log=%%i
     call :log Log saved: %TEMP%\%log%
-    goto un_exit%errorlevel%
-:un_exit0
+    if %errorlevel% equ 2 (
+        echo Intel HAXM uninstallation failed!
+        echo Please terminate the running virtual machine processes first.
+        set exit_code=1
+        goto un_exit
+    )
     :: Rename installation folder to check if any files are locked.
     for %%i in (0, 1, 2) do (
         ren %install_path% HAXM 2>nul && goto break || timeout 5 >nul
     )
-    goto un_exit3
+    echo Intel HAXM uninstallation failed!
+    echo For more details, please check the installation log: %TEMP%\%log%
+    set exit_code=1
+    goto un_exit
     :break
     if exist %install_path% rmdir /s /q %install_path%
     echo Intel HAXM uninstalled successfully!
-    goto un_end
-:un_exit1
+    goto un_exit
+:un_fail
+    call :log Permission denied
     echo Please run this command as administrator!
     set exit_code=1
-    goto un_end
-:un_exit3
-    echo Intel HAXM uninstallation failed!
-    echo For more details, please check the uninstallation log: %TEMP%\%log%
-    set exit_code=1
-    goto un_end
-:un_exit5
-:un_end
+:un_exit
     if exist %log% del /f %log%
     call :log End of uninstallation
     exit /b %exit_code%