fpcupdeluxe: WARNING: FPC Native Installer (BuildModuleCustom: FPC): Adding OVERRIDEVERSIONCHECK=1 due to wrong version of bootstrapper !!
Wrong bootstrapper. If you look close to the error log then it also states that all bets are off in such case.
Did you perhaps instructed FPCUpDeluxe to use your native installed FPC ?
fwiw: I am aware that the override is probably forced because of the new target.
Error: Path "./" does not exist
Is that perhaps your installation path that you provided with FPCUpDeluxe ? afaik it only works with fully qualified paths
Anyhows, the first order of business is always to get rid of the multithreaded build.