As discussed in previous topics, this means that some program outside of Photoshop has the file open and Photoshop cannot overwrite the file.
(more or less just what the message told you)
This is not a bug in Photoshop. All Photoshop is doing is telling you about the (external) problem.
Adobe can't do anything about other applications holding files open.
Thanks for the reply, but this doesn't help much considering that Photoshop is the app that created the file in question. the only app that has ever opened this file, and the only app capable of opening an image file that is running. This happens fairly frequently, without warning, but always involves a file that has been open in Photoshop at some point during the session but is not open at the time that the problem crops up.
If you have a Finder window open and the file you are/were editing is showing in column view, something as simple as the QuickLook service for OS X can have the file "in use" and will cause this error. I run into this all the time, because I tend to leave Finder in column view and have the preview of whatever I'm working on visible when I edit it. I'm learning to close the Finder window before doing anything to the picture though.
Like Chris said, it's not a Photoshop error. It's not a Photoshop bug. It's Photoshop telling you that somewhere in your system something has the file in use in some capacity and that it cannot be saved until that application "lets go" of it.
So how is it that Apple and Adobe haven't managed to deal with this problem by now? I believe what you're saying, but the issue only comes up in Photoshop. One might hope, therefore, that the problem would be addressed by someone sooner or later; but so far that has evidently not happened. It's a pity that the spirit of cooperation that used to exist between Apple and Adobe seems greatly diminished in recent years. Customers of both companies are the losers. You must admit, a basic problem like this shouldn't exist, regardless of where the cause lies.
This might not be such an easy thing to solve and it might be that there is a third party entity involved other than Adobe and or Apple. I once in a while encounter this problem and this is the work around I find works.
I go to the Apple Menu>Recently Open and chose one of the apps that had been opened but I closed and I select it if it is sill actually open it will come to the front right away and I quit it again I do it with all the applications opened or closed actually and that usually frees up the cache that seems to caught in the buffer.
Once I think I must have cleared this cache I then go back and usually find I an actually do a simple save or a save as and can over right the previous file without a problem. But I admit I have yet to figure out which program is causing this or if it is actually the application(s) itself or just some process that failed to stop.
Hope this helps.
Adobe has done what we can (and we're still trying to find other ways around it, like trying again after half a second) - but the files are being locked by something OUTSIDE our control.
We've notified Apple about it, and they have made several fixes over the years - but somehow the problem keeps recurring in their software.
No, this does not come up just in Photoshop. It happens in any application that actually checks for errors when saving the file. But there are many applications that don't check for such errors.
Correct, this problem should not exist. But all we can really do is tell the user when it does occur.
Adobe really needs to fix this and I'd like to tell them so.
I've run into this and I'm convinced it's not Adobe. Whenever I've gotten around the problem it's often something from Apple that got in the way.
I use a simple workaround when Finder/QuickLook isn't letting go of the file. First use a free utility like TinkerTool or Onyx to turn on the Quit command in the Finder. Whenever the Finder gives you trouble, if closing the Finder window in question doesn't solve it, just do the ol' Command-Q. It's a little faster (and maybe safer?) than force-relaunching the Finder. This usually releases files for me when all else fails; it also often cures the annoying "can't eject the volume because it's in use" messages when you've already quit every program you can find.
There's the question of why Photoshop and not others; I'm not an engineer but I think the sheer size of Photoshop files is a factor. In one instance I noticed that quicklookd was using a lot of RAM, and QuickLook has been implicated by an earlier post in this thread. It isn't unusual for a Photoshop file to be very large compared to other types of documents. It's possible that when QuickLook hits a large Photoshop file, and it does its normal thing of generating a big preview for it, it could get tied up reading that huge image long enough to block another program. Sometimes it seems like QuickLook just hangs on them. When it happens, you can try looking at Activity Monitor to see if something like QuickLook, Spotlight, or some other program is using an unusual amount of CPU or RAM.
Apple Mail (at least in 10.5) is another major offender by the way. If you attach a file to Apple Mail it will hang on to it as "open" even after you remove the attachment. Other programs will not be able to write to the file that was attached or formerly attached. Nothing short of quitting Apple Mail will make it let go of the file. You'll notice it when you delete a JPEG, PDF, Word doc (definitely not just Photoshop) attachment because you realize you need to make a change and attach it again. Attempting to export an updated one over the old one is blocked until Apple Mail is quit.
In my experience I think what Chris says is true.
Thanks for your thoughts, Conrad. I hadn't made a connection between the Photoshop issue and the Mail issue you mentioned, which still persists in Snow Leopard. Whatever the cause, it's a very frustrating problem to be sure. In Mail, of course, attachments of any size are a problem. Attached files cannot be deleted from the Desktop until Mail is closed.