Fixing Corrupt Preferences for Default Internet Helpers

Wednesday, 5 May 2004

The Problem

My preferred default FTP client is Interarchy. I switched about two months ago, after the release of Interarchy 7.

Last week, however, at some point shortly after upgrading to Interarchy 7.1.1, the setting for my preferred FTP client became unset, and, worse, I was unable to reset it to point to Interarchy. I could set it to point to any other FTP client, just not Interarchy, the one I wanted to set it to. My other helper app preferences — for my email client and web browser — were unaffected.

It was just my FTP helper, and it was only blocking me from setting it to Interarchy.

Being that it was specific to Interarchy, I of course suspected that either (a) there was some sort of bug in Interarchy 7.1.1; or (b) my copy of Interarchy had somehow become corrupted; or (c) my Interarchy preferences had somehow become corrupted (which, if true, might be a manifestation of (a), of course, but that’s not a distinction worth worrying about here).

But none of those were the source of my problem, because: (a) no other Interarchy 7 users seem to have the problem; (b) I re-downloaded and re-installed Interarchy 7.1.1, and also tried reverting to Interarchy 7.0, neither of which helped; and (c) I archived and removed my existing Interarchy preferences, letting Interarchy create fresh ones, but to no avail.

Thus, even though it was specific to Interarchy, the problem seemed to be with my Internet Config preferences.

Brief Interpolation on the History of Internet Config (Feel Free to Skip This Entire Section if You’re a Long-Time Mac User or if You’ve Arrived Here via Google and Are Just Looking for the Solution to the Same Problem I Had)

Internet Config provides a group of system-wide preferences for Internet-related stuff. You can specify default helper apps for different tasks — email, FTP, web browsing, Usenet — as well as helpers for specific protocols like ‘http:’, ‘afp:’, ‘gopher:’, etc. (These protocols aren’t even necessarily Internet-related; for example, Mac OS X’s Help Viewer is the default handler for the ‘help:’ protocol.)

In older versions of Mac OS X, you could change some of these settings via the Internet panel in System Preferences. Before that, on Mac OS 8 and 9, you used the Internet Control Panel. And back in System 7, you used the Internet Config application, which is where it started.

Internet Config wasn’t invented by Apple. It was designed, implemented, and released for free by Quinn “The Eskimo!” and Peter N Lewis. It was useful, popular, and widely supported by the developers of Internet client software for the Mac. Thus, Apple adopted it and rolled into the system.

On Panther, however, the Internet System Preferences panel is no more. The only way to see these prefs using software that ships with Panther is to use Internet Explorer. (IE not only provides a UI to modify these system-wide Internet Config settings, but it also stores its own IE-specific private preferences inside the Internet Config preferences. This always struck me as a very odd decision on the part of IE’s engineers.)

Now that the Internet System Prefs panel is gone, it’s up to individual applications to provide a way to set default protocol handlers. Thus, Safari and Apple Mail provide preferences to specify default apps for web and email. It is a bit weird to have to open Safari to tell the system that you’d rather use FireFox.

Third-party developers are forging ahead, however. Mailsmith, for example, now provides a button in its preferences window to set it as the default email client, obviating the need to do so via Apple Mail. And given that the author of Interarchy is Peter N Lewis — co-inventor of Internet Config — it’s not surprising that Interarchy 7’s preferences window allows you to specify it as the default FTP client.

The Symptoms

After the problem started, each time I launched Interarchy, it would prompt me with a dialog asking if I’d like to use Interarchy as the default FTP client. I’d click Yes, quit, relaunch, and but it would ask me again.

You can change this setting at any time using a checkbox in Interarchy’s prefs, “Use Interarchy for FTP”. Every time I opened Interarchy’s prefs window, this checkbox was unchecked. Check it, close prefs, open prefs, and it’d be unchecked again.

The preference simply could not be set.

Although Apple has eliminated the Internet System Preferences panel, it hasn’t eliminated the underlying Internet Config preferences themselves. The OS just no longer offers a user interface to see and change them. One solution, as mentioned above, is to use Internet Explorer.

A better option is to use third-party software. Alexander Clauss’s MisFox is a free application that allows you to see and change all of the important Internet Config settings: default apps, file mappings, and protocol helpers. (Clauss is the author of iCab.)

But I couldn’t set my default FTP app to Interarchy using MisFox, either. Same for Monkeyfood’s More Internet, a free System Preferences panel that lets you edit and change Internet Config’s protocol mappings. It was by using these tools that I determined that my problem affected only Interarchy, and not other FTP clients such as Transmit or Fetch.

The Solution

Although I hadn’t yet found the source of the problem, I had at least eliminated some suspsects. It was not the Interarchy application. It wasn’t Interarchy’s prefs data.

Plus, since I saw the same problem using MisFox and More Internet, I figured it must be some sort of corruption in the file — or files — that store my Internet Config settings. But what and where are those files? The only obvious one is “com.apple.internetconfig.plist”. The name is a giveaway, and the modification date changes when you make changes to Internet Config settings.

Sadly, trashing this file — then immediately logging out and logging back in — did not help. All my Internet Config prefs were reset to factory settings, but I still could not assign Interarchy as my default FTP app.

I found no other file in my home folder that had a name containing “internet” and “config”, or a modification date that changed upon making changes to Internet Config settings.

At this point, I was stuck. I was fairly certain that there were one or more other files where the system was storing Internet Config data, and that those files were in some way corrupt, but I had no more guesses left as to where those files may be. Of course I tried searching for a solution via Google, but found nothing. You know you’re in deep shit when Google doesn’t have the answer to a troubleshooting issue.

Then, I asked Rich Siegel, who suggested that the problem might be related to Launch Services. That sounded like a promising idea, and in fact proved correct.

Here’s what I did:

  1. I started by logging out and logging back in, holding down the Shift key to suppress my normal login items.

  2. I opened Terminal, and typed:

    cd /Library/Caches/

    That’s the root-level Library folder, not the Library folder in your home folder.

  3. To delete the Launch Services cache files, I typed:

    sudo rm com.apple.LaunchServices*

  4. I authenticated with my password.

  5. I immediately restarted the machine.

This fixed the problem — albeit at the expense of deleting all of my existing Launch Services preferences, which includes the mappings that bind filename extensions to default applications. A minor irritation, but certainly not a big deal.

I doubt that step #1 is necessary, but I didn’t want to take any chances by deleting the Launch Services files while other applications were running. It’s also possible that I could have simply logged out and logged back instead of restarting at step #5; but once again, why take a chance?

In hindsight, it’s easy to draw the connection between Launch Services and Internet Config. E.g., Apple’s developer introduction for Internet Config states:

Internet Config, a Mac OS 8 and 9 API, supports centralized entry and management of Internet preferences for all of a user’s Internet applications. For example, email programs and Web browsers can obtain a user’s name, email address, home page, incoming mail server, and similar preferences from one common place that is easily edited by the user via the Internet Config application.

Mac OS X applications should employ Launch Services and System Configuration for managing Internet preferences. In Mac OS X, Internet Config calls through to these newer APIs. Using them directly increases your application’s efficiency.