[Michael Sumner]

The link to the patch isn’t working for me. How do I fix this issue? It’s a problem in my activity stream as well. Thanks.

[Michael Sumner]

I just replied to a similar topic with how to fix it:
https://buddypress.org/community/groups/how-to-and-troubleshooting/forum/topic/fatal-error-when-trying-to-delete-user/

[Michael Sumner]

Open the file mentioned, and replace this:

$group_ids = $this->get_group_ids( $user_id );

with this:

$group_ids = BP_Groups_Member::get_group_ids( $user_id );

And right below that, replace this:

foreach ( $group_ids->groups as $group_id ) {

with this:

foreach ( $group_ids as $group_id ) {

That fixed the issue for me.