Thanks for the reply Gavin. You are, of course, right. I noticed this posting on the EJB3 forum just after receiving your response (I did research this problem before posting... honest): http://www.jboss.com/index.html?module=bb&op=viewtopic&t=107018 Of particular interest is a comment from Carlo de Wolf: anonymous wrote : This is not a bug. You're trying to access multiple one phase resources in a single transaction. This was allowed with the old transaction manager, but it's not allowed in the new one. It is possible to set a property in the transaction service to allow multiple one phase resources, but that could lead to transaction problems. Better use two phase resources. Now I'm a little confused as to what I should do. Naturally, I'd like to follow Carlo's advice and use "two phase resources" but I don't know what this means in the context of Seam @Asynch methods. Could you offer any advice? Cheers, Chris. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4049114#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...