AQCHEM maximum iterations exceeded


I am running CMAQv5.2.1 for nest simulation. But it crashed for certain days with the AQCHEM error: maximum iterations exceeded. There is no NaN or Infinity showing up in my log files.

I know this is caused by MCIP generated METCRO2D file. Because when I run that day with a fake METCRO2D file (copied from other days), it ran well. However, I checked the RC and RN values in the METCRO2D file. There is no negative or unreasonable large value. I don’t know what else in the METCRO2D could cause this error.

Any help is appreciate on how to solve this issue.

Thank you so much