3
Can't help you I'm afraid, but I have had exactly the same experience. I set up Donations on my live site and got exactly what you have - failure of the post back to my server from Paypal. Set it up on a test site - worked. Set it up on a rebuild of my 2.0.13 site under 2.2.3 and it didn't work. I have never been able to figure out what the problem is, and there have been tons of posts discussing similar problems. Just no solutions.
Barry Cooper
Sweet Home, Oregon