Call to undefined method views_plugin_display_block::get_cache_plugin()

Can you please test the 6.x-3.0-dev version? It should be fixed there already.

In general from my perspective it's a huge mistake to pack 6.x-3.x-alpha3 with openatrium.

Can you please show us the full error message? There is probable a bad place where this function is called.

Fatal error: Call to undefined method views_plugin_display_block::get_cache_plugin() in /var/www/......./profiles/openatrium/modules/atrium_features/atrium_activity/atrium_activity.views.inc on line 97

This is really not our fault :)

There is get_plugin('cache') which you can use. Sadly there is no issue queue for drupal.org here.

I can confirm for 6.x-3.x that switching get_cache_plugin() for get_plugin('cache') works.

I can also confirm that #7 works

Fresh install of Atrium 1.0
upon install updates were needed:
Views
Diff
Token

After updating to Views 3x Rc and Dev = error message:
Fatal error: Call to undefined method views_plugin_display_block::get_cache_plugin...

After reverting to Views 2x no error.

@DrupalConnection reread #7.

Also, Open Atrium is not necessarily Views 3 compatible. It is an advanced, development-oriented decision to actually apply any updates from the status page. While those module versions are newer, and the page declares them to be "recommended", they were not packaged as part of Atrium's current suite of Contrib and Custom modules.

I can confirm #7 fixed it for me too, and this on atrium 1.2 as well. :/

#7 fixes this for me too(Open Atrium 1.4).

So what is the point? That's still some kind of "bug" of open atrium, but they have views2 in their installation profile so i guess the version you should better use is 2.x as well.