Notices and Warnings Drupal Commons 7.x 3.9 Undefined index, invalid argument, illegal string offset I get these 7 messages every time a user goes to an event listing.
Happens in this order.  I'd like to troubleshoot and eliminate.

Notice: Undefined index: title in commons_origins_preprocess_form_content()  of profiles/commons/themes/commons/commons_origins/template.php).
Notice: Undefined index: #items in commons_events_entity_view_alter() of ….profiles/commons/modules/commons/commons_events/commons_events.module).
Warning: Invalid argument supplied for foreach() in element_children() of /includes/common.inc
Warning: Illegal string offset '#children' in drupal_render() (line 5890 ) of …includes/common.inc
Warning: Illegal string offset '#children' in drupal_render() (line 5900 ) of …includes/common.inc
Warning: Illegal string offset '#children' in drupal_render() (line 5983 ) of …includes/common.inc
Warning: Illegal string offset '#printed' in drupal_render() of /includes/common.inc).
title is not defined. #items is not defined. foreach is not getting a value to work with. #children doesn't exist to render.#printed doesn't exist to render.
go into the function where title is supposed to be defined and check that there is a value. Do the same for the rest. Check what further up the chain in your code is calling these values. Try doing a backtrace.