I'm porting the grafana snap to core20, and there is an override-build section for the grafana-ui part, which I had to switch to use npm, where `snapcraftctl build` is clearly failing, but still exiting with status 0. I added some debugging output and this is the summary (see https://pastebin.ubuntu.com/p/5C2hWcYB3b/ for better formatting): snapcraft yaml snippet: override-build: | set -x # https://forum.snapcraft.io/t/issue-with-nodejs-plugin-when-using-base-keyword/11109/8 #echo "unsafe-perm = true" > ~/.npmrc rm -rf ~/.npmrc snapcraftctl build result=$? echo "result=$result" echo "exiting now" /bin/false export PYTHON=/usr/bin/python2 ... building with --use-lxd: Launching a container. Waiting for container to be ready Waiting for network to be ready... snap "snapd" has no updates available snap "core20" has no updates available Skipping pull grafana (already ran) Skipping pull grafana-ui (already ran) Skipping pull snap-wrappers (already ran) Skipping build grafana (already ran) Building grafana-ui + rm -rf /root/.npmrc + snapcraftctl build + [ ! -f /root/parts/grafana-ui/install/bin/node ] + tar xzf - -C /root/parts/grafana-ui/install/ --strip-components=1 + curl -s https://nodejs.org/dist/v12.18.3/node-v12.18.3-linux-x64.tar.gz + npm pack . + tail -1 npm notice npm notice 📦 grafana@7.0.4 npm notice === Tarball Contents === npm notice 210B .babelrc .... .... npm notice 7.3kB public/app/features/datasources/state/actions.ts npm notice 28.9kB public/app/features/explore/state/actions.ts npm notice+ npm install -g --prefix /root/parts/grafana-ui/install grafana-7.0.4.tgz npm WARN deprecated popper.js@1.16.1: You can find the new Popper v2 at @popperjs/core, this package is dedicated to the legacy v1 npm WARN deprecated core-js@1.2.7: core-js@<3 is no longer maintained and not recommended for usage due to the number of issues. Please, upgrade your dependencies to the actual version of core-js@3. npm WARN deprecated core-js@2.6.11: core-js@<3 is no longer maintained and not recommended for usage due to the number of issues. Please, upgrade your dependencies to the actual version of core-js@3. > core-js@2.6.11 postinstall /root/parts/grafana-ui/install/lib/node_modules/grafana/node_modules/empower-core/node_modules/core-js > node -e "try{require('./postinstall')}catch(e){}" sh: 1: node: Permission denied npm WARN optional SKIPPING OPTIONAL DEPENDENCY: fsevents@~2.1.2 (node_modules/grafana/node_modules/chokidar/node_modules/fsevents): npm WARN notsup SKIPPING OPTIONAL DEPENDENCY: Unsupported platform for fsevents@2.1.3: wanted {"os":"darwin","arch":"any"} (current: {"os":"linux","arch":"x64"}) npm WARN @welldone-software/why-did-you-render@4.0.6 requires a peer of react@>=16.13 but none is installed. You must install peer dependencies yourself. npm WARN slate-react-placeholder@0.2.9 requires a peer of slate-react@>=0.22.0 but none is installed. You must install peer dependencies yourself. npm ERR! code ELIFECYCLE npm ERR! syscall spawn npm ERR! file sh npm ERR! errno ENOENT npm ERR! core-js@2.6.11 postinstall: `node -e "try{require('./postinstall')}catch(e){}"` npm ERR! spawn ENOENT npm ERR! npm ERR! Failed at the core-js@2.6.11 postinstall script. npm ERR! This is probably not a problem with npm. There is likely additional logging output above. npm ERR! A complete log of this run can be found in: npm ERR! /root/.npm/_logs/2020-10-07T19_03_58_004Z-debug.log Failed to build 'grafana-ui'. Recommended resolution: Check the build logs and ensure the part's configuration and sources are correct. + result=0 + echo result=0 + echo exiting now + /bin/false result=0 exiting now You can see I'm hitting the problem described in https://forum.snapcraft.io/t/issue-with-nodejs-plugin-when-using-base-keyword/11109/8, but snapcraftctl doesn't signal it and the build would continue were it not for my /bin/false statement to force a stop.