This error occurs when the message size limits in the CD web service configuration are too strict.
During XPMs fast track publishing process (part of the session preview mechanism) the CM cannot publish the binaries (i.e. images) on your site. Possibly one of the images on the page is too large to be published to the CD Web Service.
Check the web.config of the CD Web Service webapp (assuming the .NET version of the CD Web Service here). Try raising the
maxBufferSize. Those parameters limit the size of the request when the CM tries to fast track publishes images to the session preview mechanism on the CD web service.
By default this limit is set to 2097152 (2MB) which might a bit too small when using nice big images like the example content in DXA.
<binding name="HttpBinding" maxReceivedMessageSize="524288000" maxBufferSize="524288000">
A similar problem can occur on the CD Deployer when you try to deploy a binary which is too big.