wpkg-firefox/packages/firefox.xml

<?xml version="1.0" encoding="UTF-8"?>
<packages>
    <package id="firefox"
             name="Mozilla Firefox"
             revision="77"
             reboot="false"
             priority="10">

        <variable name="PKG_VERSION" value="52.7.3" />
        <variable name="VARIANTE" value="esr" />

        <check type="uninstall" condition="versiongreaterorequal" path="Mozilla Firefox .+" value="%PKG_VERSION%" />

        <install cmd="taskkill /F /IM Firefox.exe">
            <exit code="0" />
            <exit code="-1073741515" />
            <exit code="128" />
        </install>
        <!-- Remove x86 on x64 boxes, but ony if present -->
        <install architecture="x64" cmd='%COMSPEC% /C if exist "%PROGRAMFILES(x86)%\Mozilla Firefox\uninstall\helper.exe" "%PROGRAMFILES(x86)%\Mozilla Firefox\uninstall\helper.exe" -ms' />
	<install architecture="x86" cmd='"%SOFTWARE%\firefox\x86\Firefox Setup %PKG_VERSION%%VARIANTE%.exe" -ms' />
	<install architecture="x64" cmd='"%SOFTWARE%\firefox\x64\Firefox Setup %PKG_VERSION%%VARIANTE%.exe" -ms' />
        <!-- Empeche l'affichage d'un message d'erreur lors de l'ouverture d'une URL depuis un fichier .bat --> 
        <install cmd='%COMSPEC% /C reg add "HKCR\FirefoxURL\shell\open\ddeexec" /v "" /t REG_SZ /d "" /f' />

        <upgrade include="install" />

        <remove cmd='%COMSPEC% /C if exist "%PROGRAMFILES%\Mozilla Firefox\uninstall\helper.exe" "%PROGRAMFILES%\Mozilla Firefox\uninstall\helper.exe" -ms' /> 
    </package>
</packages>