Error using npt barostat for equilibration

I’m performing simulations on randomly oriented-buckypaper assembly. For this, I have performed energy minimization of the initial configuration followed by heating the system to 300K. Before moving to the production stage, I need to run npt equilibration. But I have encountered the following error:
ERROR: Non-numeric pressure - simulation unstable (src/fix_nh.cpp:1043)

This is the energy data before this step: (metal units)
Step Temp E_pair E_mol TotEng Press Volume
0 300.75747 -5702.1835 1564.2104 -3671.5005 -9.0991501 2.0171627e+08

Kindly suggest what could be the possible issue and solutions for the same.

Thank You

Without knowing more details about your simulation and being able to reproduce the situation, there is only guessing. The most likely issue, based on the information you provided, would be an unsuitable choice of Nose-Hoover barostat parameters, i.e. the Pdamp settting.