We use XMLHttpRequest to update one field to trigger the workflow.
It work on the on-premium but in the Dynamic CRM online 2015, if we active the workflow which monitor the specify field change,the request will return Error 500.
Is there any more info on the workflow run-page-thingy (look at process sessions). If you get the workflow to run with gui change to the field it shouldn't be a problem otherwise. Could the wf be registered in user scope?
I'm guessing a bit here since I don't have so much to work with :(