Error: Terrain correction Process


I am new to SAR Data processing. While doing Terrain correction process in Sentinel-1 Image SNAP throwing an error stated as " Type: OperatorExcption An unexpected network error occurred"

Please suggest!!

during terrain correction SNAP tries to access an online source for the digital elevation model (SRTM 3Sec AutoDownload is pre-defined).
If this server cannot be reached you will get this error. This can have several reasons.

Please try the following: Select SRTM 1Sec (AutoDownload) instead and run again, and let us know if the error persists.

Thank you very much for your reply. I did the same as you mentioned above but doing so taking huge time to write the product in folder its about three hours processing is on and from last one hour i couldn’t see any progress in it.
Even my RAM of system is 16 GB.

Please help in this.

But the network error does no longer arise?

Maybe you (un)intentionally adjusted the output pixel size?

Yes i am following one tutorial of ESA for Flood mapping and based upon that they have changed the pixel size of output (from 10 m to 70 m) During the terrain correction.

What you suggest i should not do that. Attached video link.

please try it once with the pixel size as it is suggested by SNAP. It usually takes not much more time and you can later still decrease the resolution. Once the SRTM is downloaded the TC shouldn’t take too long.

OK sure i will go with that.
Thank you.
Will contact you again either for question or thanks,


Now i have done all the steps as you suggested previously; But from the last 40 minutes process is done that much (screenshot attached.)

Almost same percentage of process was happening with ( 70 m) pixel size.

that means the writing of the product takes the longest time (not the computation itself). Is your data stored on an external drive?

No Everything stored in system internally.

please try this: Before the RD terrain correction run the multi-looking operator to reduce the pixel size to something near 70m. The product will be considerably smaller then and the terrain correction should take much less time.

Ok sure will do that.