This seems an old problem to me which occured in older versions of Jomsocial. But the bug is back. Trying to create an announcement in a group (group announcements and discussions are enabled) but get:

Page cannot be found.
Error: 1054 - Unknown column 'params' in 'field list' SQL=INSERT INTO `tdl7n_community_groups_bulletins` (`groupid`,`created_by`,`published`,`title`,`message`,`date`,`params`) VALUES ('8','42','1','Het sponsor project','

Hi Meindert,

please goto your Database, phpmyadmin maybe (depend with your hosting provider). and excute this query:

ALTER TABLE `tdl7n_community_groups_bulletins` ADD `params` TEXT NOT NULL ;

Ok that helped regarding announcements and was able to place a new announcement. But it is not working for discussions. That's logical as it makes use of other tables. Error: Unknown column 'params' in 'field list' SQL=INSERT INTO `tdl7n_community_groups_discuss` (`groupid`,`creator`,`created`,`title`,`message`,`params`,`lastreplied`) VALUES ('8','60','2014-08-29 07:41:24','Waar staat \"De Leeuwenbende\" voor? ','

So I used ALTER TABLE `tdl7n_community_groups_discuss` ADD `params` TEXT NOT NULL ;
and now everything works.
Thanks again,
Meindert