it is a memory problem - this error is discussed in detail here:
- Terrain-Correction: GC overhead limit exceeded
- S1 IW slc: GC overhead error in back geocoding
- GPT Sentinel 1 TOPSAR coherence graph: GC overhead limit exceeded
- ‘GC overhead limit exceeded’ runtime error using 'Terrain-Correction' in python
- GC overhead limit exceeded error
- ‘GC overhead limit exceeded’ runtime error using 'Terrain-Correction' in python
Is there a reason why you use SLC data instead of GRD, as you are basically creating a terrain corrected and calibrated band, you could as well use GRD and considerably reduce the processing amount.