I see you are using Elgg 1.8 (That's a very old version... I suggest to upgrade to a newer Elgg release if you can, i.e. if the plugins you absolutely need are available also for newer Elgg versions. Best would be to upgrade at least to Elgg 1.12. Such an upgrade would have to be made by upgrading to 1.9, then 1.10, 1.11, 1.12. Just a sidenote).

The Database Validator plugin is an Elgg plugin that can check (and repair) some issues that might occur with the database of your site. The database can still be fine as such but it might have some invalid entries that could result in problems. For Elgg 1.8 the version of Database Validator to use is 1.4 (https://elgg.org/plugins/438616/releases/1.4). Install the plugin like other Elgg plugins. In the admin section of your site you will find a new section then (at "Administer" - "Utilities" - "Database cleaner"). Here you can test your database for errors with "Validate". In case there are any errors found, make backup of your database and then you can do a "Repair".

I don't know if this will fix the error that shows in the group. Maybe the error is caused by the access settings of this group (closed group). Do you also get the error when logged in to your website as an administrator? Is it possible for you to find out if one of the latest content added to this group causes the error?

Tengo miedo de actualizar la versión y que se estropee el sitio.

Ya instalé el plugin. Dice que las bases de datos están OK.

El administrador y un usuario básico ven mal el grupo.

El grupo cerrado se veía bien. Cuando pulse en Make featured se estropeo.

iionly:

Muchas gracias por tu ayuda. Crearé un nuevo grupo y volcaré en él lo que había en este.