Notice: Undefined index: in entityreference_view_widget_validate

I'm not using field group, but I am using this module to set a reference on a profile2 entity and I saw the same error. Installing this patch took care of it, thanks a lot!

I have a similar problem but I'm not using the field_group module, but I am using the field_collection module. If I edit an entity reference field (using the entityreference_view_widget) which is inside a field_collection directly at the field collection url (e.g. /field-collection/field-collection-field-name/XXX/edit) then it works fine. However, if I try to edit it within the node form, then I get the above errors. In addition, the views pager doesn't work and the add and remove checkbox ajax functionality doesn't work.

The attached patch should address all of the above issues. It should work for both field collections and field groups, though admittedly I haven't tested it with field groups. In addition, it should handle with more complex setups - for example, in one instance I have an entityreference_view_widget inside a field collection which is inside yet another a multi-value field collection.

has anyone tested the above patch ?
i see lots of warnings after applying it.

thanks.

This is too big of a change for the 1.x branch which is now frozen.
Please test the 2.x branch and submit a new patch if the problem still exists there.