When performing an in-place upgrade from 10.5.2 to 10.7 you receive an error message saying:
The specified folder <Your target installation folder> is not recommended. It
already contains an Introscope install that is not eligible to be upgraded. If
you choose to install to this folder, a fresh install will be performed. Any
pre-existing files and settings in the folder will be overwritten.
Any supported platform/operating system where APM 10.5.2 is installed and running, and where an upgrade to APM 10.7 is desired to be installed, that is supported by an APM 10.7 installation
The file <em home>/UninstallerData/base/installvariables.properties may be corrupt or missing. As a default, the Enterprise Manager installer assumes that any detected previous installation is ineligible for upgrade.
Workaround: Copying the file <em home>/UninstallerData/base/installvariables.properties from another Enterprise Manager will allow you to use the installer to perform the upgrade.