---
title: Debugging logs
description: Send debugging information in an errored response to a logging service.
image: https://developers.cloudflare.com/core-services-preview.png
---

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### Tags

[ Logging ](https://developers.cloudflare.com/search/?tags=Logging)[ Response modification ](https://developers.cloudflare.com/search/?tags=Response%20modification) 

# Debugging logs

Send debugging information in an errored response to a logging service.

JavaScript

```

// Replace with your actual logging service endpoint

const loggingEndpoint = "https://your-logging-endpoint";


export default {

  async fetch(request) {

    try {

      // Attempt to fetch the request from the origin server

      const response = await fetch(request.clone());


      // Check if the response status indicates an error (for example, 4xx or 5xx)

      if (!response.ok) {

        // Prepare error details and context for logging

        const errorDetails = {

          status: response.status,

          statusText: response.statusText,

          url: request.url,

          method: request.method,

          headers: Object.fromEntries(request.headers),

        };


        // Log error details to your logging service

        await logError(errorDetails);


        // Return the original response with status and statusText intact

        return new Response(response.body, {

          status: response.status,

          statusText: response.statusText,

          headers: response.headers,

        });

      }


      // Return the successful response from the origin server

      return response;

    } catch (error) {

      // Handle any exceptions that occur during fetch

      const errorDetails = {

        message: error.message,

        stack: error.stack,

        url: request.url,

        method: request.method,

        headers: Object.fromEntries(request.headers),

      };


      // Log error details to your logging service

      await logError(errorDetails);


      // Return a generic error response

      return new Response("Internal Server Error", {

        status: 500,

      });

    }

  },

};


// Function to log error details to your logging service

async function logError(details) {

  try {

    const response = await fetch(loggingEndpoint, {

      method: "POST",

      headers: {

        "Content-Type": "application/json",

      },

      body: JSON.stringify(details),

    });


    if (!response.ok) {

      console.error("Failed to log error:", response.statusText);

    }

  } catch (error) {

    console.error("Error logging error:", error.message);

  }

}


```

```json
{"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"item":{"@id":"/directory/","name":"Directory"}},{"@type":"ListItem","position":2,"item":{"@id":"/rules/","name":"Rules"}},{"@type":"ListItem","position":3,"item":{"@id":"/rules/snippets/","name":"Cloudflare Snippets"}},{"@type":"ListItem","position":4,"item":{"@id":"/rules/snippets/examples/","name":"Snippets examples"}},{"@type":"ListItem","position":5,"item":{"@id":"/rules/snippets/examples/debugging-logs/","name":"Debugging logs"}}]}
```