Started getting this error on a GL-MT300N-V2 after a few plugin downloads. I read from the wiki that 3 means "Could not create temporary directory", suspecting having run out of memory I checked and there's plenty of memory left unused, also by removing previously installed plugins the error persists. As of now if I try opkg update from the cli I get xsystem: wget: Child killed by signal 11 for any repository. What could it be?
OpenWrt 19.07.8 r11364-ef56c85848 / LuCI openwrt-19.07 branch git-21.189.23240-7b931da