The error message occurred because the Id property was being mapped twice.
In our mapping class we had this
_modelMapper.BeforeMapClass += (modelInspector, type, classCustomizer) => classCustomizer.Id(type.GetProperty("Id"), (idMapper) =>
{
idMapper.Access(Accessor.Property);
idMapper.Generator(Generators.GuidComb);
});
Then we tried mapping Id again as a property of the CustomRevisionEntity
The final mapping:
_modelMapper.Class<CustomRevisionEntity>(entity =>
{
entity.Id<int>(x => x.Id, mapper => mapper.Generator(Generators.Identity));
entity.Property(x => x.RevisionDate);
entity.Property(x => x.UserIdentityId);
});