Unable to upload posts through this plugin

Hello,

I am trying to upload a xml file from my old wordpress site to new one, but every time when I have upload the file, there showing an error which shown bellow

“The site is experiencing technical difficulties. Please check your site admin email inbox for instructions”

But I haven’t received any kind of email for the same.
all the media file are uploaded perfectly, but post not, if I select the All content option.

If I have select the only post option then they will be upload perfectly. but media files are missing at that time. I want to upload all the content together because all the media files are atteched to the some of the post.