Is there something wrong with the Export Web Map Task hosted on utility.arcgisonline.com? I had been using that for my web app's printing service but it doesn't seem to be working anymore; I get an error in Firebug that just says:
[object Object]
.cache["dojo/errors/create"]/</</r()/3.8/ (line 221)
h()
I tried switching to the export web map task hosted on sampleserver6.arcgisonline.com and that one works, so I'm pretty sure it's not something in my code.