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What Are MIME Types?

A Multi-Purpose Internet Mail Extension (eg. “application/octet-stream”), also known as a MIME, is type of Internet standard originally developed to allow the exchange of different types of data files through e-mail messages. MIME types like application/octet-stream are classified into specific data categories such as Video, Audio, Image, and many more. This categorization provides instructions to your computer or mobile device about how these files should be opened / viewed.

Why Do I Need MIME Types Like application/octet-stream?

Categorizing MIME types like application/octet-stream into a data type such as “Application” allows your e-mail client or Internet browser to display the content as intended. For example, when you attach a digital camera photo file to an e-mail, an Image MIME type will be associated with that file to allow your recipient to view the photograph.

Here's how it works: Web servers (computers that host websites and e-mail) insert a set of MIME instructions into the beginning of a data transmission, such as an e-mail message or webpage, in the following format:

Content-Type: application/octet-stream

[Format Explanation: The MIME type, which in this example is “Application”, is separated by a forward slash (“/”) and followed by a subtype.]

This set of instructions tells your client application, such as an e-mail program (eg. Microsoft Outlook, Apple Mail) or web browser (eg. Google Chrome, Mozilla Firefox), which “player application” should be used to properly display the application/octet-stream content.

Many modern web browsers include built-in components to display common data types such as image players (eg. GIF, JPEG), Adobe Flash Player, Javascript, and many more. Other less-common types of players must be downloaded separately in order to properly display the MIME content.

What Are The Most Common Problems Associated With application/octet-stream?

Sometimes you’ll find that your web browser or e-mail client is unable to properly display your application/octet-stream content. This could be due to one of two reasons:

1. You are missing the proper Application “player software” to display the application/octet-stream content.

2. Your Windows Registry contains an incorrect file extension (eg. XLS, PDF) association with the application/octet-stream MIME type.

How To Fix application/octet-stream Issues

Do I have the application/octet-stream “player application” installed?

The first step in troubleshooting issues with opening application/octet-stream content is to first make sure that you have the correct “player application” installed for this MIME type. Because there can be several (or even hundreds) of related software applications to application/octet-stream, it is very difficult for us to compile a comprehensive list.

Therefore, a key strategy in determining the correct application is to look for clues on what software programs might be related to application/octet-stream. Look at the naming of the subtype for clues about a related program (eg. Word, Excel) or software developer name (eg. Microsoft).

Furthermore, if you’ve been sent MIME type application/octet-stream as an e-mail attachment, look for the file extension of the attached file. This file extension (eg. PKG, LHA, LZH, etc.) can provide you with a clue of what “player application” is associated with this Application MIME. Take a look at our file extension list below to see if there are any clues to finding the right “player application”.

Do I have broken application/octet-stream file associations?

The second step in troubleshooting application/octet-stream issues is making sure that you have correct file associations in the Windows Registry. Installing and uninstalling programs can lead to incorrect file associations with application/octet-stream. Take a look at your Windows Registry settings to ensure that the MIME type is correctly associated with the “player application” and file extension.

WARNING: DO NOT edit the Windows Registry unless you are an advanced computer user with experience editing the Registry. Making an error in editing the Registry can create irreversible damage to your PC.

If you are not comfortable editing the Windows Registry, we highly recommend using an automated registry cleaning program, or taking you computer to a qualified professional.

Did your computer fail to open an OCTET-STREAM file? We explain what OCTET-STREAM files are and recommend software that we know can open or convert your OCTET-STREAM files.

What is an OCTET-STREAM file?

The OCTET-STREAM format is used for file attachments on the Web with an unknown file type. These .octet-stream files are arbitrary binary data files that may be in any multimedia format. The OCTET-STREAM format was developed for Web browsers to understand that the file attachment is in an unknown file type, which also allows the user to choose to download and save the attached file in any file format that the user wants.

In other instances, the OCTET-STREAM file format is used to inform the user that the attached file may be saved in a recommended file format. This also allows the Web browser to enable the user to know the recommended file format for the attached .octet-stream file.

These OCTET-STREAM files may be opened by renaming the extension of the attached file to a specific file extension, and then by using an application with support for opening such files. For example, an .octet-stream file may be renamed to a .txt file (if it is indeed a .txt file), and Notepad may then be used to open the file. This means the user needs to know the file type of the attached .octet-stream file before renaming the file in the correct file extension.

Software that will open, convert or fix OCTET-STREAM files

Unfortunately we have not received enough suggestions for software that can open OCTET-STREAM files yet.

Try a universal file viewer

I would suggest that you try a universal file viewer like Free File Viewer. It can open over 200 different types of files - and very likely yours too! Download Free File Viewer.