Why was FTK version 6.3.1 released after version 6.4.0?
Version 6.4.0 is the latest version of FTK with regards to features and is also the latest database schema version.
The 6.3.1 version was released due to a reported problem with permissions not being set correctly on restored cases.
Please see the release notes of 6.3.1 for more detail.
Who Should Install 6.3.1?
If you are currently using FTK 6.3.0 and plan to stay on the 6.3 database schema, then it is suggested that you consider upgrading to the 6.3.1 version.
Note about upgrading from 6.3.0 to 6.3.1:
Do not uninstall the database. Uninstall only the FTK 6.3.0 interface and the processing engine.
Then, install the FTK interface and processing engine from the 6.3.1 version iso.