When I upgrade from Openads 2.0, it says by geotargeting settings won't be migrated. Why?

There are several possible error messages you might be seeing here depending on the type of geotargetting database you are using, these include:
MaxMind

• "A GeoIP database is not readable."
• "A GeoIP database malformed."
• "A GeoIP database was not found."

If you see any of these messages, for whatever reason, your MaxMind geotargeting database cannot be correctly read by Openads 2.4. You can safely proceed with the upgrade, however, once the upgrade is completed, you must log in as the admin user, and go to Settings, Main Settings, Geotargeting Settings, and re-configure the path(s) to your MaxMind geotargeting database(s).
Ip2Country

• "The Ip2Country geotargeting database is no longer supported."

Unfortunately, Openads 2.4 no longer supports the Ip2Country geotargeting database. You can safely proceed with the upgrade, however, once the upgrade is completed, you will not have any geotargeting support. If you wish to have geotargeting support, you will need to obtain a copy of the MaxMind country geotargeting database. MaxMind have both a free and paid for version of this database.

Please note that in both of the above cases, any banners that you have targeted to geotargeting data (for example, if you have a banner set to deliver only when the country is equal to the USA), will not deliver after you have upgraded until you re-configure the geotargeting database(s).