Stability of standing flux-antiflux front in anisotropic layered superconductors is considered. We describe two assisting mechanisms destabilizing the standing vortex-antivortex front. There are anisotropy of the layered superconductors and the heat, released by the vortex-antivortex annihilation. We present the phase diagram of  the front stability for various anisotropy and heating intensity parameters. We predict that even small vortex-antivortex heating can result in front instability. The characteristic size of the unstable pattern is estimated.