Cannot use WhatsApp in Gingerbread anymore
Yes, officially they said they won't support android 2.1 and 2.2, but since the last update only devices with Android 4.0 and above are supported.

Try installing 2.16.259 over 2.16.225:


Download APKs for WhatsApp version 2.16.225 and 2.16.259.
Install 225 first, don't open it
Reboot the phone
Install 259


But soon or later these versions will be dropped as well.