What is MIME type "application/x-ms-etl"?

A MIME type is a string that tells browsers and other tools how to handle a particular kind of file.

application/x-ms-etl is a MIME type for Event Trace Log files.
These files record system and application events on Windows. They capture detailed performance data and errors in real time.
This format is essential for diagnosing issues and monitoring system behavior.

Tracks and logs system performance data.
Assists in debugging and troubleshooting.
Records events from Windows services and applications.
Needs specialized tools to view and analyze the data.

Files with the extension ETL are associated with this MIME type.
For more details, visit the Microsoft Event Tracing documentation.

Associated file extensions

.etl

Usage Examples

HTTP Header

When serving content with this MIME type, set the Content-Type header:


    Content-Type: application/x-ms-etl

HTML

In HTML, you can specify the MIME type in various elements:


    <a href="file.dat" type="application/x-ms-etl">Download file</a>

Server-side (Node.js)

Setting the Content-Type header in Node.js:


    const http = require('http');    
    
    http.createServer((req, res) => {    
      res.setHeader('Content-Type', 'application/x-ms-etl');    
      res.end('Content here');    
    }).listen(3000);

Associated file extensions

.etl

FAQs

How do I open an application/x-ms-etl file?

You cannot open these files with a standard text editor; they require specialized Windows tools. The most common applications are Windows Performance Analyzer (WPA), which is part of the Windows Assessment and Deployment Kit (ADK), or the built-in Event Viewer. You can also use the command-line tool tracerpt to convert the binary data into readable text formats.

Can web browsers display .etl files directly?

No, web browsers do not have native support for rendering Event Trace Log files. If a server sends a file with the application/x-ms-etl MIME type, the browser will typically prompt the user to download and save the file to their disk rather than displaying it in a tab.

How do I configure IIS to serve .etl files?

By default, IIS may block unknown file extensions. To allow downloads, add the MIME type to your web.config file inside the <staticContent> section: <mimeMap fileExtension=".etl" mimeType="application/x-ms-etl" />. This ensures the server delivers the file correctly instead of returning a 404 error.

Are there security risks associated with sharing ETL files?

Yes, ETL files can contain sensitive system information, file paths, and potentially Personally Identifiable Information (PII) depending on what providers were traced. You should analyze the contents using a tool like Network Monitor or WPA to ensure no confidential data is exposed before sharing these logs publicly or with third-party support.

How do I convert an ETL file to CSV or XML?

You can use the native Windows command-line tool tracerpt. Running the command tracerpt filename.etl -o output.csv -of CSV will convert the binary log into a Comma-Separated Values file. Similarly, you can generate an XML summary report to analyze the data in other applications.

Why does my web server return a 404 error for .etl files?

Web servers like IIS and Nginx often refuse to serve files with extensions they do not recognize for security reasons. To fix this, you must explicitly add the application/x-ms-etl MIME type mapping for the .etl extension in your server configuration.

Is application/x-ms-etl the only MIME type for Event Trace Logs?

While application/x-ms-etl is the specific vendor type for Microsoft Event Trace Logs, you might occasionally see generic binary types like application/octet-stream used if the server is unconfigured. However, using the specific x-ms-etl subtype is recommended to help client operating systems identify the correct application to launch.

General FAQ

What is a MIME type?

A MIME (Multipurpose Internet Mail Extensions) type is a standard that indicates the nature and format of a document, file, or assortment of bytes. MIME types are defined and standardized in IETF's RFC 6838.

MIME types are important because they help browsers and servers understand how to process a file. When a browser receives a file from a server, it uses the MIME type to determine how to display or handle the content, whether it's an image to display, a PDF to open in a viewer, or a video to play.

MIME types consist of a type and a subtype, separated by a slash (e.g., text/html, image/jpeg, application/pdf). Some MIME types also include optional parameters.

How do I find the MIME type for a file?

You can check the file extension or use a file identification tool such as file --mime-type on the command line. Many programming languages also provide libraries to detect MIME types.

Why are multiple MIME types listed for one extension?

Different applications and historical conventions may use alternative MIME identifiers for the same kind of file. Showing them all helps ensure compatibility across systems.