Hi all, I've just come back to OpenWrt after several years, to try and update to 21.02 some older images which I had built for the last time back in 2017 (LEDE era) for ath79 and x86.
Without seeing the error logs, it's a bit hard to know why it fails.
run again the build with make -j1 V=ss > build_log.txt
it will remain black for a while as it's building on a single core (to have a readable log) and when it has done (or also while it is running, if you open another terminal window), you can open the file build_log.txt and see what errors it shows.