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When the site finishes building, click the URL and check that it built correctly.
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A Warning About Deploying from Netlify:
If the developer deploys directly from Netlify without going through the special “Deploy on Netlify” button, the form with the environment variables will not appear, and the site will be built with no environment variables, which will of course cause it to error out. The user must then troubleshoot as shown above to set the environment variables manually.