On Step 3 of 1.2.3 in the upgrade guide, I'm getting a
System.OutOfMemoryException pointing to
Sitecore.Update.Utils.FileUtils.SerializeFile(Stream stream, String location) +137.
Installation wizard installed fine and the
UpdateInstallationWizard.aspx page comes up fine.
/sitecore/admin/packages, it looks like, it tried to write the file "Upgrade from 8.1 rev. 160519 to 8.2 rev. 160720.update", but it's got zero length.