Error in solvation step using OPLS FF

ERROR 1 [file unk.itp, line 45]:
I am facing this error when I am doing simulation using OPLS force field and topology files generated using Ligpargen

Atom index (2) in bonds out of bounds (1-0).
This probably means that you have inserted topology section “bonds”
in a part belonging to a different molecule than you intended to.
In that case move the “bonds” section to the right molecule.