How to determine which Vercel Deployment introduced an issue?

With Vercel Preview Deployments and bisecting, you can quickly and efficiently determine which commit introduced a regression in your application, and then instantly rollback.

Watch a video tutorial or learn more in the following guide.

vercel bisect
Vercel CLI command to search for first bad deployment

Use Vercel Bisect to find first broken deployment

Vercel Bisect is a command, inspired by the git bisect command, that helps identify the first Deployment an issue was introduced by traversing a range of preview deployments, marking them as either "good" or "bad". This tool was released in version 24 of the CLI.

To start your debugging session, run vc bisect in the terminal and you will be given an interactive prompt to help find where the bad commit was introduced. Start with a deployment URL where the bug occurs. Next, specify a deployment URL where the bug does not occur. Lastly, specify a subpath to narrow down by page, such as /login or /.

Vercel Bisect will retrieve a list of deployments for you to review, starting in the middle of the list, utilizing a Binary Search. At each step, you’ll indicate if the deployment is “good” or “bad” to quickly narrow down to the root cause The number of steps left will be visible. After the full list of deployments has been traversed, the first bad deployment will be shown with the date, commit with message, and URL to inspect the deployment on the dashboard.

You can then instantly rollback to a previous deployment with Vercel.

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