...
The log file will contain more details about why the install failed.
Failure to decrypt existing configuration file
This may occur in a multiple scan engine environment if a config file for one server has been accidentally copied to another server. The database connection string is encrypted using a key derived from the local Windows system and cannot be moved between systems. In this case the install.log will contain an error like the following: (note that additional line breaks have been added for readability)
...