Graph Builder_Co registering Sentinal-1 TOPS

Hi All, actually I’m new in SNAP or STEP, i tried to co register multiple images using graph builder and I’m getting Error (java.lang.NullPointerException)

another thing is there any way to do the co registration for between images covering the same area but in different sub swath?

any one could help?

Thanks
MOHAMMED

Are you sure that isn’t a memory issue?
In this case you could try to separate your graph in two part: one with Read, Split and Orbital correction, another part only with back-geocoding.

Thank you annamaria, i don’t think it is a memory issue as i have work station with 96 GB RAM and available space around 1.5 TB
I’ll try to separate the graph as you suggested .