An AJAX HTTP error occurred using commerce coupon percentage I'm able to create coupons with no errors. When I enter coupon code into the field and click on the submit button I get the following error.

An AJAX HTTP error occurred.
HTTP Result Code: 500
Debugging information follows.
Path: /system/ajax
StatusText: Service unavailable (with message)
ResponseText:


Drupal version 7.28

Commerce Coupon Percentage 7.x-1.0-beta7

dblog messages

// first error
Rules Warning:
  Unable to get a data value.
Error: 
  Unable to get the data property code as the parent data structure is not set.
// second error
Rules Warning:
  Unable to evaluate condition commerce_coupon_discount_coupon_codes_exist_on_order.
// second error
PHP Error:
  EntityMetadataWrapperException:
  Unable to get the data property coupon_id as the parent data structure is not set.
  in EntityStructureWrapper-&gt;getPropertyValue()(line 438 of /homepages/
  36/d385915579/htdocs/bbp/sites/all/modules/entity/includes/entity.wrapper.inc).
This seems an error in Commerce Coupon Percentage module. Your problem comes from the EntityMetadataWrapperException: when processing the AJAx petition something goes wrong and an Exception is throw. This is fatal, so Apache ends the petition with the status 500.

I think this a bug in the module code, so you may go the issue queue for this module and create a new bug report with your problem. 

By the way, the Commerce Coupon Percentage is only comptabible with Commerce Coupon 1.x, check your are using a 1.x release.