A custom MIME filter is disabled and not invoked in Internet Explorer 9

You have a custom MIME filter that meets the following conditions:

• The MIME filter is expected to be registered and unregistered dynamically in a WebBrowser control host application.
• The WebBrowser control browses to local content by using a file protocol.

When you use this custom MIME filter in Windows Internet Explorer 9, you may notice that the MIME filter is disabled and is not invoked.

This issue occurs when the response that contains the MIME type is returned, and Internet Explorer cannot find a registered MIME filter for the MIME type.

Note�If you use Windows Internet Explorer 8, the custom MIME filter is always invoked.

To resolve this problem, install this update. After you install this update, you must enable the hotfix.

Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base: To enable the hotfix, follow these steps:

1. Start Registry Editor. To do this, click Start, click Run, type regedit, and then click OK.
2. Locate and then click to select the following registry subkey.�
   For 32-bit:
   
   
   
   HKEY_LOCAL_MACHINE\Software\Microsoft\Internet Explorer\Main\FeatureControl
   
   
   For 64 bit:
   
   HKEY_LOCAL_MACHINE\Software\Wow6432Node\Microsoft\Internet Explorer\Main\FeatureControl
3. After you select the subkey that is specified in step 2, point to New on the Edit menu, and then click Key.
4. Type FEATURE_ENABLE_CUSTOM_MIME_FILTER_RELOAD_FOR_KB2628551, and then press Enter.
5. Right-click the FEATURE_ENABLE_CUSTOM_MIME_FILTER_RELOAD_FOR_KB2628551 entry, point to New on the Edit menu, and then click DWORD Value.
6. Type iexplore.exe, and then press Enter.
7. Right-click iexplore.exe, and then click Modify.
8. In the Value data box, type 1, and then click OK.
9. On the File menu, click Exit to exit Registry Editor.

Security update information

To resolve this issue, install the most recent cumulative security update for Internet Explorer. To do this, visit the following Microsoft website:For more technical information about the most recent cumulative security update for Internet Explorer, visit the following Microsoft website:
Note This update was first included in security update 2618444.

For more information, click the following article number to view the article in the Microsoft Knowledge Base:

To work around this issue, make sure that the MIME filter is always registered.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

For more information about the MIME filter, visit the following Microsoft Developer Network (MSDN) website:For more information about the WebBrowser control, visit the following MSDN website:For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base: