Error message linking a C++ Builder 10.1 Berlin project

Question

[ilink32 Error] Error: Unresolved external '__fastcall System::Variant::Exec(System::AutoCmd&, int) const' referenced from

I am getting the above error message when I am trying to use the new 32-bit compiler in C++ Builder 10.1 Berlin instead of the classic compiler. This same piece of code compiles successfully using the classic compiler.

I know something is probably missing (a lib?), but what?

Any idea?