The option is undocumented because I don't want to feel pressure to keep it. The change from February in which SQLite started converting invalid surrogates into 0xfffd has been rescinded. It will not be in the upcoming release. This is because it broke Firefox, and if it broke the Firefox code, then there are probably many other applications that it will break as well. So it is a dead issue at this point. The old implementation is retained inside the #ifdef as a comment, in case I can think of a way to resurrect it in the future. But for the upcoming release, it is as if this feature had never been added. Hence, no documentation and no support.