Google App Engine - The engine "node" is incompatible with this module - node.js

Question

This questions has been asked many times already, and I checked all the answers but none of them helped me.
I'm trying to deploy a NodeJs app to GAE using a app.yml file. It was working perfectly until my last Github PR on it where I upgraded some nodes modules.
Now I'm getting the Error The engine "node" is incompatible with this module. Expected version "16.x.x". Got "12.19.0".
As you can see I'm up to date on my computer. I also removed and install Node, Npm and Yarn tonight just to be sure.
node -v
v16.15.0
npm -v
8.5.5
yarn -v
1.22.18
I tried deploying the app with a specific node version on my packages.json but with or without it's not working.
"engines": {
"node": "16.x.x"
},
I also tried to remove the cache on GAE using this, without no effect.
default_expiration: '0d 0h'
On my app.yml I'm using nodejs en Env: flex:
runtime: nodejs
env: flex
I can't use node16 as I need env: flex.
Of course I tried to delete the Node_modules and yarn.lock for at least 100 times but still nothing, always the same error.
Nothing change on the app.yml file since the last deployment. The only thing is that I upgraded some Node Modules.
On the Yarn side I've tried:
yarn install --force
yarn install --ignore-engines
yarn cache clean --all
But still not working.
Any help will be really grateful.

Answer 1

I had the same issue. The error is because the image used by google is fixed to the version 12.19.0, check here for more info.
My workaround was use a custom image:
Change in the app.yaml file the runtime to custom.
runtime: custom
env: flex
...
Create a Dockerfile file with the following content:
FROM gcr.io/google_appengine/nodejs
# Current Node LTS version.
RUN /usr/local/bin/install_node '16.16.0'
RUN npm install --unsafe-perm --global yarn
COPY . /app/
RUN yarn install --production || \
((if [ -f yarn-error.log ]; then \
cat yarn-error.log; \
fi) && false)
CMD yarn start