Get download error message - but can open download ok

Question

When I download a file from the Internet (using Firefox 3.6.8) I always get the same error message: /Users/Home Folder/Downloads/example subject 7.pdf could not be opened, because an unknown error occurred.
Try saving to disk first and then opening the file.
Yet when I open up the Downloads Folder I can open the file just fine.
Any ideas of how I can fix this glitch?
Thanks,
Danty

Answer 1

If emptying the Firefox cache doesn't work, you may try to find out
what application is set by Firefox to handle the .PDF component
of the process whereby the Firefox browser has another app open
the .PDF. You can choose within the Firefox preference settings to
have certain apps (listed in the Firefox settings) handle certain kinds
of files. By default, some kinds of the common ones formerly dealt
with automatically by older versions of Firefox are not set to do any.
Perhaps a review of Firefox' own settings in its applications, may help.
It may be something else. The browser version reflects new changes.
Since I've always used the option, for the sake of security, for .PDF
and other items to download first and then I can choose to see if I
want to open them, this kind of issue has not been a problem for me.
The 'Clear Recent History' in my Firefox 3.6.8 browser also clears the
Cache and most other items. I use it manually as well as have it set
to clear many things when I close or quit the browser. That may help.
{There also could be a matter in how the Firefox app was installed; if it
were installed via another user account, or if there is another issue in
this matter not directly related to the browser; but in the user accounts.}
I wonder what is selected by your browser as the default handling agent
of the .PDF files. And if you have Preview set, or if you have Acrobat
(reader) also available to the System, as a choice to open those files.
The ability to choose or not choose may be what is messed up. And in
the case of a browser, this choice is done within Firefox browser settings.
There are support files, not where your Firefox bookmarks are kept, that
could be corrupted; and if you totally uninstall Firefox except for your
bookmarks files, then re-install, (and check Firefox apps pref settings)
it may be the final means of correcting such an issue, if it persists.
Once an item has gone through the Download manager, it would be
available to the Finder to handle the file with whatever defaults you
or the system have set to open or read such content.
I've never had that kind of error message, though; even when the more
recent Firefox browser's apps settings were not set to use a chosen app
to perform a function in unison with the browser's newer listed capabilities.
So, that is an odd matter to behold... Could there be a need to perform
general routine and preventative system maintenance on the OS X?
Good luck & happy computing!