Self Solution!
My mistake, apparently D13Slideshow from the server where wordpress is installed uses the url name to retrieve images.
In my case, I have altered the hosts file from my computer because https://www.mysite.com is not yet redirected to the Ip where wordpress was installed. Every works fine in wordpress, but when the plugin d13slideshow tried to recover images from the posts in https://www.mysite.com, offcourse there no wordpress in such place, so the error in line 538 is that… failed to open stram… etc. So, you must alter the hosts file in the server too, or just change the dns server definitely.
I think this is probable a common issue or mistake taken when someone install a wordpress in a testing environment and then want to move it to a production enviroment having de minor possible downtime from the original old site.
So… I think this post could be useful to someone… if so say it!.