Can I Open an InDesign Lock (IDLK) File?
ZD wrote: Can I open an InDesign lock file? How? This is a great idea for one of our podcast's obscure feature of the weeek-eek-eek, but I'm just going to...
ZD wrote:
Can I open an InDesign lock file? How?
This is a great idea for one of our podcast’s obscure feature of the weeek-eek-eek, but I’m just going to dive in and answer it here for all our readers. Whenever you open an InDesign file, the program creates a “lock” file — with an “.idlk” file name extension — in the same folder.

When I started using InDesign, I tried everything to open this file, assuming that there must be some kind of magic in there. After all, some programs do store recovery data in temporary files such as this, in case you crash.
However, if you check, you’ll probably find that this file is always zero K large. Nothign is stored in there (at least nothing that I know of). When I asked an Adobe engineer about it, he told me that the IDLK file is used simply as a marker to indicate that the file is open.
Why would such a thing be necessary? Because InDesign files are actually databases of information, and like other databases, more than one user can open them at the same time. Adobe realized that this could cause some, um, challenges, especially if two people were trying to make changes to the same file. The solution: Create a little file that alerts InDesign that the file is open and others shouldn’t change it. When you close the file, the lock file goes away.
If InDesign crashes, it does attempt to recover the work you did, but it uses Recovery Data files in your preferences folder. You may find idlk files in directories even when InDesign isn’t running; that typically indicates that you had crashed at some point and the idlk file was never deleted. Feel free to delete them yourself at that point.
This article was last modified on December 18, 2021
This article was first published on October 23, 2007
