If you’ve been using Adobe Lightroom since Beta 1, as I have, and if you’re using a Mac, there is a very good chance that you’ve run into the awful “change modules” error. This error usually strikes when your catalog is being updated during a version upgrade, when other Adobe software on your computer changes, or for any number of other unrelated reasons (as I discovered).

What happens is roughly this: you open the program and the splash screen remains indefinitely. If you click it, it disappears, but Lightroom’s main window does not open. You receive a very minimal menu bar including “Lightroom,” “File,” “Edit,” and perhaps “Window.” The File menu is shortened and only allows you to open a catalog. I presume that this is what Lightroom would look like if you could put it into a state where it has no catalog open. During normal operation, you basically always have a catalog open.

Once there, you can try to open your catalog, but as soon as you do, you will receive the error: “An error occurred when attempting to change modules.” Feel free to click OK on that message, it will simply drop you into a weird, incomplete Lightroom interface that has no side panels and no film strip.

Having battled this error two different times now, I am confident I can offer some advice.

The first time I encountered this error was in Lightroom 1.1. I normally import my photos using Image Capture so they receive custom icons (Image Capture’s cool like that) and I had just finished importing a big batch from a recent trip up to Boston. Opening Lightroom, I received the Terrible Module Error and the incomplete Lightroom interface that I might be tempted to call “the gray screen of death.” At first I had a panic attack because I’ve put so much into my Lightroom catalog since Beta 1. I have so much metadata it hurts to think about losing it.

Reinstallation of the software is usually step number one when this type of thing happens, and it’s one of the most widely suggested remedies on the Adobe User-to-User Forums and on the one or two Flickr discussion threads where it has come up. Between you and me, it doesn’t work. I’ve been through this error twice and both times I faced it, reinstalling the software a few times didn’t solve it. But it can’t hurt, right?

If you want to reinstall Lightroom all over again, here is what you have to do:

  • Delete the Lightroom application. Go into your Applications folder, drag Lightroom to the trash, and empty the trash. Or, if you’re a slick keyboard nerd, select Lightroom and press Command-Delete (that’s the key that old-schoolers call “backspace'). Don’t forget to empty the trash either way.
  • Delete the Lightroom preferences file. Go into your home folder, then into Library -> Preferences, and delete @com.adobe.Lightroom.plist@ from within it using one of the methods above.
  • For giggles, you can also delete the Lightroom support folder if you want, which is located in home -> Library -> Application Support -> Adobe -> Lightroom.
  • Last, but definitely not least, you need to delete the installation receipt, which is what tells the Lightroom installer that the software is already installed. It will not let you reinstall it if it finds the receipt. Open up your hard drive then open Library -> Receipts and delete @Adobe Photoshop Lightroom.pkg@.

Once you’ve done all that and your trash is empty, you can install the software again. But like I said, it’s probably not going to help you.

The first time I solved this problem, it was a stroke of luck. I had reinstalled the software a couple of times to no avail and I was getting to the end of my leash. Each time, however, I installed version 1.0 off of my retail CD and then immediately upgraded to 1.1 using the downloaded upgrade app. Eventually I got a clue and figured I’d try installing 1.0 and actually running it before upgrading just to see what would happen. So I did that and I got an entirely different error. This time it said “There isn’t sufficient hard drive space for Lightroom to open” or something like that.


Sure enough, importing my last batch of photos completely filled my hard drive. Once I fixed that problem by deleting a bunch of really bad music, the error went away and I was back up and running with version 1.1. This is a symptom of pretty bad error trapping by Adobe’s development team. Obviously the hard drive being full caused some type of exception, but rather than that error bubbling up to the GUI level, it proceeded to cause a cascade of problems until the very last issue was reported to me, which had to do with changing modules.

That would be like going to the doctor and having him tell you that your eyes are red because of sinus pressure or something. That’s interesting and all, but wouldn’t it be better if he could tell you that your eyes are red because you have sinus pressure, which is because you have a cold? That makes it a bit easier to treat the problem, wouldn’t you say?

It seems to me that the main reason why this error is seen so often and in so many varying situations is because it’s the very last thing that goes wrong in nearly every chain of exceptions within the software. Bad exception handling.

Okay, that’s all well and good, but I did have this happen to me again (last night, actually). This time it was version 1.2 I was using and this time my hard drive was clearly not full. I even double-checked it. So, once again I hit Google to try to find out what other sorts of problems people have had. There is remarkably little to be found on this issue. I did find some interesting suggestions, but none of them worked for me.

I had messed around a lot with installing different versions of Photoshop and the Creative Suite (as I mentioned in my recent article Photoshop CS3: Overrated) and figured that all of that activity with related Adobe software probably messed up some files somewhere. So, I performed one of the tests outlined by someone on the Adobe forums.

I created a new user on my system, granting them administrator rights, and I logged into their account and ran Lightroom. It ran! This narrowed the problem down to something in my local home directory because both users were administrators and had access to every other file on the system. So, I copied the Lightroom preferences file and a couple of other files from the new user’s Library folder into my own Library folder, hoping that it would solve the problem. No such luck. Back to the drawing board.

Having no other apparent course of action, I searched out and deleted every single Adobe-related file on my entire computer. I wiped it all out completely.

I even restarted, which I really think is unnecessary, and installed Lightroom for only the fourth or fifth time that night. And I got the same error! By that time I was getting pretty desperate. The one thing I hadn’t tried was messing with my actual catalog files. I was very apprehensive about touching them because, well, they’re my lifeblood.

What I did was, I renamed my whole Lightroom folder to @Lightroom.old@ and started it up. BAM, it created a new, empty, default catalog and opened like a champ. Go figure. With the program still open, I deleted the Lightroom folder and renamed @Lightroom.old@ back to @Lightroom@. Then I was able to go through File -> Open and open my actual catalog and guess what? It worked.

There is something tremendously fishy about this whole situation, but I hope that my experience with it will help folks out there who have run across this problem and spent late nights banging their heads against their desks as I did.

If you have run into this problem, solved it, or not solved it, leave a comment!