When Asterisk 10 is run, as part of the initialization process it checks for the existence of the SQLite3 database. If it doesn't exist and an old-style Berkeley DB does exist, it will attempt to convert the Berkeley DB to the SQLite3 format. If no existing database exists, a new SQLite 3 database will be created. If the conversion fails, a warning will be displayed with instructions describing possible fixes and Asterisk will exit.
It is important that you perform the upgrade process at the same permission level that you expect Asterisk to run at. For example, if you upgrade as root, but run Asterisk as a user with lower permissions, the SQLite3 database created as part of the upgrade will not be able to be accessed by Asterisk.
./configure displays the warning: *** Please install the SQLite3 development package.