Hello,
I made custom form, where I use #ajax form attribute. I've noticed that it works with ie9 and ie10 but with ie7 and ie8 it shows "An error occured while attempting to process /system/ajax". After that I have uninstalled my theme and module and tried with ctools_ajax_sample module and got same error in multistep form.
When I have update my drupal core with 7.21 it works fine.
Does anybody have such issue with ie8 (I have IE8 on windows XP) ?
Thanks,
Eugene