Problem with interferometry

Hello. I am new beginner user of SNAP and i want to make basic interferometry from two Sentinel 1 pictures like in tutorial. But an erroe ocurred (See in the picure). Maybe someone can tell what that means and waht to do.

And is there any option that can devide the picture in smaller parts by my choice from which i can make interferometry?

This is memory related, please see here:

You can split the data in swaths and bursts first. Keep in mind that there might be some shifts between scenes so you have to make sure (when choosing bursts) that they are overlapping.