npm run deploy outputs "[email protected]: Permission denied (publickey)" with ssh key

Question

---

tldr

I have tried many approaches troubleshooting npm run deploy to deploy using SSH on GitHub Pages and it gives the error:

[email protected]: Permission denied (publickey).
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.

---

Thankfully, I have implemented a solution with a manual work around: https://stackoverflow.com/questions/75075815/gh-pages-permission-denied/78201454#78201454

Also, npm run deploy does work if I use HTTPS instead of SSH by running the following command:

git remote set-url origin https://github.com/my-github-username/repository.git

followed by:

npm run deploy

However, npm run deploy does not work with SSH.

Here are the steps I have taken to troubleshoot:

1. Checked my SSH key configuration on my local machine. I have verivied by running:

ssh -T [email protected]

and it outputs

Hi my-github-username. You've successfully authenticated, but GitHub does not provide shell access.

2. Verify access to the repo that I am deploying to with the command:

git remote -v

3. Made sure the deployment script in my package.json is correct. Here is my package.json file:

{
  "homepage": "https://my-github-username.github.io/repo-name/",
  "name": "react-portfolio",
  "version": "0.1.0",
  "private": true,
  "dependencies": {
    "@primer/octicons-react": "^17.12.0",
    "@testing-library/jest-dom": "^5.16.4",
    "@testing-library/react": "^11.1.0",
    "@testing-library/user-event": "^13.5.0",
    "axios": "^1.3.3",
    "bootstrap": "^3.4.1",
    "cors": "^2.8.5",
    "emailjs-com": "^3.2.0",
    "jquery": "^3.6.3",
    "nodemailer": "^6.9.1",
    "now-ui-kit": "^1.3.0",
    "react": "^17.0.2",
    "react-bootstrap": "^2.7.2",
    "react-dom": "^17.0.2",
    "react-router-dom": "^6.11.2",
    "react-scripts": "^2.1.3",
    "react-social-icons": "^5.15.0",
    "reactstrap": "^9.2.0",
    "web-vitals": "^2.1.4"
  },
  "scripts": {
    "predeploy": "npm run build",
    "deploy": "gh-pages -d build",
    "start": "react-scripts start",
    "build": "react-scripts build",
    "test": "react-scripts test",
    "eject": "react-scripts eject"
  },
  "eslintConfig": {
    "extends": [
      "react-app",
      "react-app/jest"
    ]
  },
  "browserslist": {
    "production": [
      ">0.2%",
      "not dead",
      "not op_mini all"
    ],
    "development": [
      "last 1 chrome version",
      "last 1 firefox version",
      "last 1 safari version"
    ]
  },
  "devDependencies": {
    "gh-pages": "^5.0.0",
    "sass": "^1.58.3"
  }
}

4. Checked the GitHub pages settings to make sure that I am deploying to the correct branch.

5. Ensured that the access tokens are correctly set up with the permissions needed.

Please, I am curious as to why SSH just does not work.