Investigate JavaScript errors

Open Site health, choose the Pixel, then select Errors. This page lists JavaScript errors collected after Error tracking is enabled. See Set up Site health if you need to activate it.

Review the error list

1. Choose the date range at the top of the page.
2. Use the chart to see when new error groups appeared.
3. Filter the list by All kinds, Error, or Unhandled rejection.
4. Sort by Most recent to investigate a new issue, or Most frequent to prioritize a recurring one.

Each row represents a group of matching errors, rather than one occurrence. The list shows:

• the error message and, when available, its source file and position;
• the error type;
• how many times it occurred;
• how many website paths were affected;
• when CJM last saw it.

Open an error

Select an error row to open its details. Use this information when reporting the issue to the person who manages the website:

• Source identifies the file and, when available, the line and column.
• Occurrences shows how often the grouped error was collected.
• First seen and Last seen help relate the error to a deployment or a recent change.
• Affected pages lists the website paths where the error occurred.
• Stack trace may show the browser's call sequence when it was available.

The detail is evidence for investigation, not a correction tool. A missing source or stack trace means the browser did not provide that detail; it does not mean the error did not happen.

If errors are missing

Check that the correct Pixel is selected, Error tracking is active, and the date range includes visits after activation. Earlier errors are not recovered. Test only on a safe environment when intentionally reproducing an error.

Error messages and stack traces can contain text produced by the website. Avoid putting contact or form data in website error messages, and share error details only with people who need to investigate them.