LG UP error 0x5319 is a triggered when the firmware’s digital signature or anti-rollback version is incompatible with the phone’s current bootloader state. The most common fix is to flash an official, newer KDZ with the same or higher anti-rollback version for your exact LG model. Attempting to force older firmware will result in a permanent hard brick. Always verify ARB and model compatibility before flashing.
What is your and the firmware version you are trying to flash? I can help you find the exact file match. lg up error 0x5319