@BHAWNA GUPTA the message above is shown on xschem startup, and it is due to some changes occurred to the top.sch file that is loaded on startup. When installing open_pdks made some changes on the top schematic incorrectly deleting part of the file, so some remaining lines are not understood by xschem. This is not a critical error, i have the same warnings until i fix the top.sch file. So after starting xschem please load one of the example files, like

sky130_tests/test_nmos.sch

, try to press the 'Netlist' button, then check if in

~/.xschem/simulations

a

test_nmos.spice

file is generated. Then if previous step was successful you can press 'Simulate' to run ngspice on the produced netlist. If anything fails in above steps please post some relevant information, so i can help. I am also doing a fresh and new installation of open_pdks, just to check if there are critical issues. It takes some hours on my old hardware. I know @Tim Edwards is working hard to make the new set of skywater models available (the continuous models as opposed to the 'binned' models) and still providing (for backward compatibility) the old models. May be this work can introduce some glitches in the installation, so i am trying the new install. The continuous modelset is one of the most wanted and awaited improvements of the skywater pdk, and deployment is getting delayed by Google.