Dense homogeneous fabric composed from continuous bead-free erbium-doped sodium potassium niobate (Er:NKN) 100 m long and 100-200 nm in diameter nanofibers was sintered by sol-gel calcination assisted electrospinning technique. X-ray diffraction revealed preferential cube-on-cube [001]-directional growth of fibers containing predominantly monoclinic Na0.35K0.65NbO3-type phase and significantly less of tetragonal NbO2, cubic Er2O3, and monoclinic ErNbO4 phases. Er doping with the concentration of 2 at.% provides readily detectable room-temperature broad-band photoluminescence (PL) centered at (PL) = 0.55 and 0.98 m being pumped, respectively, with 532 and 785 nm lasers. Impedance spectroscopy and static electrical tests revealed ferroelectric properties, electric field induced resistance switching and strong rectification effect in nanoporous sandwich Au/Er:NKN/Pt capacitive cell. Memristor-type current-voltage (I-V) characteristics originate from the electrochemical migration of oxygen vacancies at the n-type NKN oxide/high work function Pt cathode junction interface.