@User there are multiple issues with resistor models and the pdk in general: • the model equations use 'temp' as the temperature variable, while in ngspice this variable is named 'temper' • if you do a .param temp=27 in your spice deck you will have no more errors, however no temperature dependence is simulated. • I have a patch file that fixes the 'temp->temper' issue, (go into sky130_fd_pr dir and do patch -p1 < patch_file) among other things, see README

Thank you.