I Understand that there are other threads about this. I have disabled the various security plugins. I have reset the file folder permissions and am still getting the 400 error. It gets past step 1 and stops on step 2 with that error. Please advise what I can do to solve this? I have imported numerous sites into other WordPress installs.
Both of these are server related.
You can check with your host to see if the domain is being blocked or if they have any security rules in place that restrict XML uploads or limits the upload size.