Sir Dance A Lot

PS after installing version version 2.1.6 the popup windows are always shows to the right of the date box and therefore go off screen- so this is not good a good solution.

I have the same problems with Version 2.2.0 , I use the the actual “Google Calendar Events” widget, showing month grid view and it:
-Back and next just links to current page followed by /# – nothing happens when clicked
-hover over all calendar dates does not do a pop up
So I delete Version 2.2.0 and uploaded version 2.1.6 from development zip
WORKS!
-Back and next links to current page followed by /# BUT the javascript WORKS and back/next calender month is shown
-hover over all calendar dates javascript popup works

Same thing here.
It took me 4 hours to narrow it down to iThemes security, but exactly like you, has soon as I deactivated iThemes security, woocommerce worked again.
And it was only the ajax that had a problem, add to cart button and checkout Place Order button.

Well, did remove and delete the plugin, then re-installed it fresh from WordPress – still did not work. I was busy with other things so I left it.
Today, it’s working again??
I have done some updates with other plugins a couple of days ago, but style sheet changer was still not working. Then today, it just started working again?? I swear i did not changes anything but content today?
I’s a great plugin, keep up the good work.

All I can say to Mvdw is that I personally deactivated and deleted the plugin with a “YES” to delete plugin data question and it DID NOT delete my woocommerce products,coupons,orders,categories….
What it did delete was the woocommerce plugin “settings” only.
All your stuff is safe in your wordpress database and is not changed or deleted by deactivating& deleting woocommerce.
I have tried many different plugins in my time with wordpress and fine that the database gets a lot of unused data in it because of this, but it is better than accidentally deleting your data. Several plugins including woocommerce commonly ask you to deactivate your plugins and I have never had a problem with my data.
You should however always make a backup — I use “Updraftplus Backup/Restore” plugin to do my backups – its easy.

The way I got back to 2.0.20 was to – download the zip file from developers tab at top of page to my PC. Then in wordpress backend I deactivated and deleted the woocommerce plugin. When it asked if I wanted to delete the data I said yes. (I understand this “data” is only the woocommerce settings)(I use a wordpress multi/network site, not sure if that makes any difference). I wanted to do a fresh install of woocommerce v2.0.20 programs and settings, but of course all my products, coupons, orders etc are all intact. Then I installed woocommerce from my saved zip file and networked activated it. I when into the woocommerce admin settings and reset everything to the way it was before, not that many settings need to be changed. I use PayPal standard. The last thing to do was to figure out what pages the new version deleted, and then re-create them and add them back to my custom menus, and change the woocommerce page settings.
Everything worked after that – back on version 2.0.20

Thanks for the reply, but I don’t think it is a theme or plugin compatibility problem. My theme and template files are not out of date.
But I have done some customizing of the template files and use function.php to customize the admin area. I have used :
woocommerce_checkout_update_order_meta
woocommerce_admin_order_data_after_billing_address
These add fields to the order meta and then show these additional fields in the woo-commerce admin area. The code works fine in ver2.0.20. but in ver2.1 the order page stops displaying just after the billing address. The php code is based your documentation: https://docs.woothemes.com/document/tutorial-customising-checkout-fields-using-actions-and-filters/

Did the action/filter change??
Does your documentation need updating – a big task with so many changes I’m sure.