Same issue as described here but there was no resolution listed
www.jomsocial.com/forum/installation/354...defined-error#170230

Extentions > Manage [search for multi ] = Multilingual Status
enabled for me by default, disabling had no effect

Jomsocial 4.2.5
Joomla! 3.6.4

To reproduce simply just try to login with Facebook and error happens immediately.
Cleared both Cache and Expired Cache.

This did resolve the issue for me

~LN 35-40
//******************************************************************************************************
// REMOVED AS PER SUGGESTED BY www.jomsocial.com/forum/installation/354...defined-error#170230
// 'bio' => 'FIELD_ABOUTME',
//******************************************************************************************************

~LN 70-80
//******************************************************************************************************
// REMOVED AS PER SUGGESTED BY www.jomsocial.com/forum/installation/354...defined-error#170230
$param = '/me?fields=first_name,last_name,birthday,location,gender,name,link,bio,website,education,email,picture.type(square)';
//******************************************************************************************************
// replaced above with below
$param = '/me?fields=first_name,last_name,birthday,location,gender,name,link,website,education,email,picture.type(square)';