Changes
Added two quotemarks to avoid the error that '<' cannot be used in attributes.
<install cmd='msiexec /q /i "%SOFTWARE%\adobereader\AcroRead.msi" allusers=1'>
<exit code="0" />
<exit code="0" reboot="true " />
</install>
<remove cmd='MsiExec.exe /q /x{AC76BA86-7AD7-1033-7B44-A80000000002}' />
<upgrade cmd='msiexec /q /i "%SOFTWARE%\adobereader\AcroRead.msi" allusers=1'>
<exit code="0" />
<exit code="0" reboot="true " />
</upgrade>
</package>