Yarn add - Private package - 404 Not Found - yarnpkg

Question

I want to install a private package hosted on an internal Gitlab with Yarn.
So, I configured my .npmrc with this informations :
#mypackage:registry=https://gitlab.intra/api/v4/packages/npm/
//gitlab.intra/api/v4/projects/819/packages/npm/:_authToken=xxxxx
//gitlab.intra/api/v4/packages/npm/:_authToken=xxxxx
always-auth=true
When I attempt to install the package with yarn add #mypackage/lib-node-client, Yarn give me an error :
Trace:
Error: https://gitlab.intra/api/v4/projects/725/packages/npm/#mypackage/lib-node-common/-/#mypackage/lib-node-common-21.7.1.tgz: Request failed "404 Not Found"
at ResponseError.ExtendableBuiltin (/usr/lib/node_modules/yarn/lib/cli.js:696:66)
at new ResponseError (/usr/lib/node_modules/yarn/lib/cli.js:802:124)
at Request.<anonymous> (/usr/lib/node_modules/yarn/lib/cli.js:67062:16)
at Request.emit (node:events:369:20)
at Request.module.exports.Request.onRequestResponse (/usr/lib/node_modules/yarn/lib/cli.js:141640:10)
at ClientRequest.emit (node:events:369:20)
at HTTPParser.parserOnIncomingClient (node:_http_client:646:27)
at HTTPParser.parserOnHeadersComplete (node:_http_common:129:17)
at HTTPParser.execute (<anonymous>)
at TLSSocket.socketOnData (node:_http_client:512:22)
So, Yarn can't find the URL : https://gitlab.intra/api/v4/projects/725/packages/npm/#mypackage/lib-node-common/-/#mypackage/lib-node-common-21.7.1.tgz
If I try to get this on my browser, I can download the package...
If anyone can help me please, thank's for all :)

Answer 1

In your .npmrc file, you tell how to connect to GitLab for the project 819. The error is about the project 725. GitLab simply refuse the connexion.
Try with
#mypackage:registry=https://gitlab.intra/api/v4/packages/npm/
//gitlab.intra/api/v4/projects/725/packages/npm/:_authToken=xxxxx
//gitlab.intra/api/v4/projects/819/packages/npm/:_authToken=xxxxx
//gitlab.intra/api/v4/packages/npm/:_authToken=xxxxx
always-auth=true

Answer 2

We had a gitlab private package registry, and was constantly getting this error.
npm i #placeholder/package-name works fine, but yarn add #placeholder/package-name was giving 404 errors.
I tried all possible solutions listed on this thread. At last, there was a section in gitlab on troubleshooting yarn installation [1].
It said,
try adding this to your .npmrc file (and replace <your_token> with your personal access token or deploy token):
//gitlab.example.com/api/v4/projects/:_authToken=<your_token>
Our previous .npmrc looked like this
save-exact=true
unsafe-perm=true
#placeholder:registry=https://gitlab.com/api/v4/packages/npm/
//gitlab.com/api/v4/packages/npm/:_authToken=${PLACEHOLDER_TOKEN}
With the above new line addition, it looked like this,
save-exact=true
unsafe-perm=true
#placeholder:registry=https://gitlab.com/api/v4/packages/npm/
//gitlab.com/api/v4/packages/npm/:_authToken=${PLACEHOLDER_TOKEN}
//gitlab.com/api/v4/projects/:_authToken=${PLACEHOLDER_TOKEN}
With that addition, yarn add #placeholder/package-name worked fine.
[1] https://docs.gitlab.com/ee/user/packages/npm_registry/#error-running-yarn-with-the-package-registry-for-npm-registry

Answer 3

This should be the accepted answer. //gitlab.com/api/v4/projects/:_authToken=${PLACEHOLDER_TOKEN} Was the piece I was missing, which supercedes needing to list each project id as in Joel's answer.