Netlify Deploy Preview Not Working

Troubleshooting Netlify Deploy Preview Issues

Netlify deploy previews are a crucial part of the modern web development workflow, allowing you to preview changes before merging them into your main branch. However, sometimes these previews don't work as expected. This article outlines common causes and practical solutions to get your deploy previews back on track.

Common Causes and Solutions

• Incorrect Netlify Configuration: Double-check your netlify.toml file (if you're using one) for errors. Ensure the publish directory is correctly defined and that any build commands are accurate. A typo can easily break the entire build process.
• Build Errors: Review your Netlify build logs in the Netlify UI. These logs often contain detailed error messages that pinpoint the exact cause of the failure. Look for messages related to dependency installation, compilation, or any custom scripts you're running. For example, a missing dependency might throw an error like "Module not found: Can't resolve 'my-missing-module'".
• Git Branch Issues: Verify that the branch you're expecting the deploy preview from is correctly linked to your Netlify site. In Netlify's "Branch deploys" settings, ensure the correct branch is selected. If you've recently renamed or deleted a branch, update your Netlify configuration accordingly.
• Cache Problems: Sometimes, outdated cached data can cause issues. Try clearing your Netlify cache and redeploying. You can find the "Clear cache and deploy site" option under the "Deploys" tab in the Netlify UI. This forces a fresh build from scratch.
• Conflicting Plugins: If you're using Netlify plugins, a conflict between them or an outdated plugin version could be the culprit. Try disabling plugins one by one to identify the problematic one. Check the plugin's documentation for known issues or updates.

Advanced Troubleshooting Steps

If the basic solutions don't resolve the issue, consider these more advanced troubleshooting steps:

1. Reproduce Locally: Try running the same build commands locally that Netlify uses. This helps isolate whether the problem is with your code or with the Netlify environment. For example, if your build command is npm run build, run that locally to see if you get the same errors.
2. Check Environment Variables: Ensure that all necessary environment variables are correctly configured in your Netlify settings. Incorrect or missing environment variables can cause build failures or runtime errors. Remember that environment variables are case-sensitive.
3. Contact Netlify Support: If you've exhausted all other options, reach out to Netlify support for assistance. Provide them with detailed information about your issue, including your site name, build logs, and any steps you've already taken to troubleshoot. Include the last deploy ID (a unique identifier for each deploy).

By systematically investigating these potential causes, you can effectively diagnose and resolve most Netlify deploy preview issues, ensuring a smooth and efficient development workflow.