Where does Windows store its "Open With" settings?

windows registry file-extension file-type
mitch picture mitch · Oct 13, 2010 · Viewed 48.8k times · Source

I'm trying to programmatically check file associations by the file extension (for example .jnlp files). I keep reading that

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\JNLPFile\Shell\Open\Command

is the Registry key to check. However, if you change the association through Windows Explorer:

Open With > Choose Program > (Always use the selected program)

the change isn't at all reflected in this Registry key. Where else is this information stored?

Answer

Michael Goldshteyn picture Michael Goldshteyn · Oct 13, 2010

Take a look in: 

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\

and the sub-key of that is the extension you reassigned. Under that there will be the UserChoice and OpenWithList sub-keys which will contain your redefinition.

You may also want to read http://support.microsoft.com/kb/950505 which talks about your issue.

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