Help with "Inconsistent Residue Types" Error

Hello everyone,

I am encountering a consistent issue when running simulations with both the Amber99SB-ILDN and Charmm36 force fields. Despite defining the C- and N-terminals of my protein for Charmm36, I receive the following error:

Fatal error: The residues in the chain CU400–H0402 do not have a consistent type.
The first residue has type ‘Ion’, while residue HD402 is of type ‘Other’.
Either there is a mistake in your chain, or it includes nonstandard residue names that have not yet been added to the residuetypes.dat file in the GROMACS library directory.
If there are other molecules such as ligands, they should not have the same chain ID as the adjacent protein chain since it’s a separate molecule.

I’ve checked my topology files and tried different force fields, but the issue persists. Could anyone advise on how to resolve this error, particularly regarding nonstandard residue names or chain assignments?

Thank you in advance for your help!

As I wrote in Error Coordinat not matching gromacs - #18 by MagnusL, the problem is in your PDB file.