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You can monitor or review the progress of building or running your deployment to check for possible errors or build failures.

  • For build failures, review the logs for the build step to identify when and why it failed
  • For deployment errors displayed at runtime in the browser, you can monitor the developer tools console in the browser
  • If your project uses Serverless Functions, you can inspect the Function logs for any API call that your deployment calls on that page

Vercel provides access to two types of logs in the dashboard:

You can access these logs by selecting "View Build Logs" or "View Function Logs" from the Project Overview page.

The view logs buttons available on a Vercel project.

The Build Logs can be found under Overview > Deployment status > Building.

Build logs on the Deployment view.

Build logs are generated at build time for all Deployments. The logs are similar to the output of your framework's Build Command, with a few minor additions from the Vercel build system. Once a build is complete, no new logs will be recorded.

In addition to the list of build actions, you can also find errors or warnings. These are highlighted with different colors, such as yellow for warnings and red for errors. You can use this color coding to quickly identify the cause of any failed builds and areas that you may wish to investigate further. Build logs are stored indefinitely on each Deployment.

Note: The Build Logs will automatically be truncated, if the total size reaches over 4MB.

The Function Logs are under the Functions tab. You can access the Serverless Functions logs page either from the Project view by clicking on the "View Function Logs" button or from the Deployment view by clicking on the "Functions" tab.

Functions tab on the Deployment View.

Function logs provide logging output for your Serverless Functions. This includes user logging such as console.log and details of the request made to the Serverless Function.

All Function logs are generated on-demand. You can only see the logs for a Serverless Function when this Serverless Function is executed in the browser, and a response is returned. These logs are not stored and will be lost as soon as you navigate away from the Serverless Functions logs page.

Requests to cache or static assets are also not stored and never shown. Those are always persisted. The only exception to this is the failed invocations of Serverless Functions.

Note: The Serverless Function logs will automatically be cut-off if the total size reaches over 4KB.

The realtime logs of incoming requests arriving to Functions.

On this page, you can view the real-time logs of the Serverless Functions in your Deployment. You can also filter them by a specific Serverless Function.

Click the "Show Details" button to get more information.

Details for incoming request to a Serverless Function.

The following fields describe every incoming request to the Serverless Function:

  • Function Status: The HTTP response status code for the function.
  • Edge Status: The HTTP response status code for the Edge function.
  • Duration: The time it took the Serverless Function to execute.
  • Init Duration: The time it took the Serverless Function to boot up when it's "cold". If the Serverless Function is "hot" then Init Duration will be N/A.
  • Memory Used: The amount of allocated memory to run the Serverless Function.
  • ID: Unique ID assigned to this Serverless Function.
  • User Agent: The User Agent request header.

The Vercel platform, by default, stores the following:

  • Failed invocations from Serverless Functions (when the Serverless Function throws an error)
  • Build Logs

To store all runtime logs for Serverless Functions with Vercel, taking advantage of Log Drains through third-party solutions is recommended.

The Integrations Marketplace has several third-party Logging integrations ready to integrate with Vercel. Once installed, all of your logs will be available on the third-party service. Learn more about getting started on each Logging integration.

If the Logging Integration you are looking for is not available, please submit a feature request.