Up to and including AI v 8.3, we had been able to perform upgrades of our product successfully using just the stock "install per-machine" or "install for this user" settings (no special permissions on any items in the APPDIR, etc.)
After that, including AI v 8.7, upgrades fail with the following error message on Windows 7:
"Error writing to file e:\simutext\imageformats\qgif4.dll. Verify that you have access to that directory"
"simutext" is the APPDIR properly set in the project, and the imageformats folder is the first file/folder in the APPDIR. qgif4.dll is the first file in that folder. So the permission failure seems to be happening on the first file that the installer attempts to replace during the upgrade.
The upgrade process has been set to install the upgrade first, and remove the old version second. We had previously used remove first/install second, but that also generates the same error.
This particular example comes from our USB drive installation setup, but we get the same problem when the program is installed normally on the C: drive per-machine with admin access, and is being upgraded with the same level of access.
Any guidance would be most welcome, as we had a system that worked before and now doesn't, and don't know what has changed or what we should change.
Two logs are attached for your review.