The associated helper application does not exist

This article deals with the message "(filename) could not be opened, because the associated helper application does not exist. Change the association in your preferences." Firefox stores file type and application associations separately than Internet Explorer does, which can explain why one would work and not the other.[1]

Application uninstalled

This error message can mean that the program that Firefox thinks should open a specific type of file is no longer installed. You can reconfigure Firefox to use a different program:

• Firefox 2: Tools -> Options -> Content -> File Types -> Manage
• Firefox 1.5: Tools -> Options -> Downloads -> View and Edit Actions

Find the entry relating to the file type you're trying to open, then click Change Action... and pick the application you want to handle that type.

See also

• File types and download actions
• Download Actions list is empty