what's the meaning of this error?

[youngjfly]

Traceback (most recent call last):
  File "opt_CoFe.py", line 99, in ?
    runtime_parameters = runtime_params
NLInternalError: Quasi Newton minimization unable to reach minimum with given force tolerance.


after optimizing the geometry,here comes the error.i don't know what to do .
somebody help me ,thanks very much

[Nordland]

It means that it was not possible to relaxe the system to the degree specified. Meaning that after all the relaxation steps the forces are still larger than the criteria specified by you.

[youngjfly]

thank you N