To enable iCal output, this view's Format must be configured to Show: iCal Entity.

I'll be happy to fix the dependencies, but I need to know what version of Views you had before. I wasn't even aware that there was a version requirement, since I've had Views 3.5 installed since I started working with Date iCal.

I also had this problem using Views 7.x-3.3 -- updated to 7.x-3.5, and it now works properly.

Thank you! I'll set Views 7.x-3.5 as the minimum requirement.

I'm getting this error on a fresh install with both date_ical-7.x-2.12 and the latest 7.x-2.x-dev running Drupal 7.22 with Views 7.x-3.7.

This is also throwing the debug message from date_ical_plugin_style_ical_feed.inc:

Debug:

views_plugin_style_ical_feed: This style plugin supports only iCal Entity row and iCal Fields plugins.

in date_ical_plugin_style_ical_feed->render() (line 89 of .../date_ical/includes/date_ical_plugin_style_ical_feed.inc).

I've attached a screen shot showing that I do have the iCal Entity row style. I get the same error using the iCal Fields display.

I did some more debugging, and discovered that $this->row_plugin->plugin_name is still set to node_rss, even though I've clearly selected date_ical (as you can see in the screenshot.)

Thank you for the debugging you've already done! The fact that the plugin_name is not acting normally suggests to me that your Master view display may be interfering with your "Feed" display. Try this: Go to admin/structure/views/settings on your site and check the "Always show the master display" option, then click "Save configuration". Now check your view again, and you'll see a new display called Master. If that display is set to the RSS Feed style, that could be the problem.

If that's not it, I have no idea what could be wrong, so the best advice I can give is to perform a full cache clear. If that doesn't work, I'm stumped. And since it's a problem with the plugin_name variable, I don't think Date iCal can do anything about it. Views sets that value; Date iCal just reads it.

Master doesn't have the options for feeds, since it's not a feed. Clearing caches doesn't help, either. I tried that first.

Your comment made me think to look at what Views export might say. Here's the relevant portion, and it looks okay:

/* Display: Feed */
$handler = $view->new_display('feed', 'Feed', 'feed_1');
$handler->display->display_options['pager']['type'] = 'some';
$handler->display->display_options['style_plugin'] = 'date_ical';
$handler->display->display_options['style_options']['cal_name'] = '';
$handler->display->display_options['style_options']['no_calname'] = 0;
$handler->display->display_options['style_options']['disable_webcal'] = 0;
$handler->display->display_options['row_plugin'] = 'date_ical';
$handler->display->display_options['row_options']['date_field'] = 'field_data_field_event_date.field_event_date_value';
$handler->display->display_options['row_options']['summary_field'] = 'default_title';
$handler->display->display_options['row_options']['location_field'] = 'field_data_field_location.field_location';
$handler->display->display_options['path'] = 'events/feed';

Note that both style_plugin and row_plugin names are correct here.

I tried a quick reversion back to views-7.x-3.5 since earlier comments on this issue said that works, but I still get the same results, so it wasn't caused in a change between 3.5 and 3.7 releases.

Well, this just seems impossible. If even Views Export is saying the plugin_name is correct, then how the hell is it being reported wrong to Date iCal? I double-checked, and Date iCal never alters that value; it only reads it.

Have you got any other modules installed which might somehow be messing with this workflow? That's the last thing I can think of that could possibly be causing this problem.

Have you tried re-installing your site from scratch? That's obviously the nuclear option, but this is just insane, and I have no other advice.

I tried disabling a couple of other modules (Draggable Views and Services Views) yesterday to no avail. Took another look and tried disabling Views Bulk Operations today. Turns out, that was the culprit.

Moving this back to fixed for now. May open a new issue against VBO and reference this one, though. Depends on how much time I have and whether or not I can live without VBO on this project.

EDIT: I re-enabled VBO and the feed still works correctly now.

I'm very glad this has been resolved! I'm guessing that VBO has some kind of bug somewhere that got it into a broken state, but which got cleared out when the module got reset. If you grep through their code for "plugin_name", I bet you'll find something that changes it by mistake (perhaps an assignment operator where a comparison operator was intended).

In case anyone gets the original error and is in a situation where they are stuck using an older version of Views, here's a patch that seems to get the iCal Fields plugin working, at least. The patch applies to Date iCal 7.x-3.0.

Obviously, updating Views is the recommended way to go though.