Minecraft Launcher Error 5 Fix

Script for performing Mojang 'Temporary Solution'

Wifey hit with known unfixed bug

So that's it. There's a bug in the latest iterations of the Minecraft Native Launcher for Windows that goes like this (https://bugs.mojang.com/browse/MCL-5291) :

When the launcher needs to update, it downloads a copy to "%MinecraftInstallDir%\tmp\tmpLauncher.tmp". This is actually the new version of MinecraftLauncher.exe.

It then attempts to replace the current launcher at "\%MinecraftInstallDir%MinecraftLauncher.exe" with the downloaded temp file.

This is when users are seeing an 'Error 5' (Which, to me is 'Access Denied', but may be completely unrelated).

A lot of sites suggest that you should delete the temp file and try again, which some users have reported success with but what I'm reading in the updateLog.txt doesn't seem to match. The one solution that I find definitely works is to manually copy over the file as suggested in the "temporary" solution from Mojang.

This issue has reoccurred nearly every update and the bug doesn't seem to be going away, so..,

No Darling, I said 'Batch... it...'

Copy and paste this into notepad and save.

Rename .bat instead of .txt. 

When the error displays, close and 'Run as administrator' on batch file.

@echo off
:: Admin Test
"%systemroot%\system32\reg.exe" query "HKU\S-1-5-19\Environment" > NUL
If Not %ERRORLEVEL% EQU 0 (
Cls & Echo You must have administrator rights to continue.
Echo Please close and restart this batch file by
Echo right-clicking and select 'Run as administrator'.
Pause & Exit
)

:: Set Paths
if exist "%PROGRAMFILES(x86)%" (
Set MCLPath="%PROGRAMFILES(x86)%\Minecraft\MinecraftLauncher.exe"
Set MCTPath="%PROGRAMFILES(x86)%\Minecraft\tmp\tmpLauncher.tmp"
) else (
Set MCLPath="%PROGRAMFILES%\Minecraft\MinecraftLauncher.exe"
Set MCTPath="%PROGRAMFILES%\Minecraft\tmp\tmpLauncher.tmp"
)

::Check files exist
if NOT exist %MCLPath% ( echo Minecraft.exe not found at %MCLPath% & pause & exit )
if NOT exist %MCTPath% ( echo tmpLauncher.tmp not found at %MCTPath% & pause & exit )

:Copy and overwrite
copy /y %MCTPath% %MCLPath%

:Launch
%MCLPath%

exit