G_mmpbsa analysis

GROMACS version:2020

I was following the tutorial of g_mmpbsa provided by rashmikumari . I followed all the steps while installaing . after running all the executable command i faced this error.

Failed to execute command: $APBS pZ4C8ECA.in --output-file=pZ4C8EC.out
For more information and tips for troubleshooting, please check the GROMACS
website at Common Errors — GROMACS webpage https://www.gromacs.org documentation

gmx_mmpbsa is separate from GROMACS. That is almost certainly the reason why no-one has been able to answer your question here. I would advice you to contact the gmx_mmpbsa users/developers.