Screen Capture Can't Be Saved

After upgrading my iMac to OS X Lion (10.7) everything works (or at least seems to work), until I tried to do a screen capture with the built-in tools.

Things that worked:

• Capturing the entire desktop to file
• Capturing a selection (using the cross-hair) to file
• Capturing the entire desktop to the clipboard
• Capturing a selection (using the cross-hair) to the clipboard

Things that didn't work:

• Capturing entire windows to file or the clipboard (SHIFT-COMMAND-4 + SPACE / SHIFT-COMMAND-3 + SPACE)

All I got was a weird notification box with the message:

Screen capture can't be saved

The console application also showed an error message:

12/16/11 1:40:08.762  com.apple.SystemUIServer.agent: screencapture could not capture window 3c

Lurking around the Interwebs, I found this seem to occur after an upgrade of the OS, but real solutions are hard to come by.

This is what I did to solve my problem:

• Remove the screencapture PLIST (preferences) file (~/Library/Preferences/com.apple.screencapture.plist)
• Copy a com.apple.screencapture.plist file from a working OS X Lion environment and place it in the correct location on the troubled OS X installation.

That seemed to result in two com.apple.screencapture.plist files (one with an additional extension of .locked). I removed the .locked file, rebooted the iMac, and screen capture worked again.

I must mention that I didn't see the .locked file initially. Could be that it existed before. In which case I probably did more than was required to get things fixed....

Update on Thursday, February 2, 2012 at 20:29 by Willem

Turned out that the .plist problem wasn't the cause of my problems, since I ran into the problem again today.

For some reason the capturing of Windows (SHIFT-COMMAND-4 -> SPACE) borked again. So I tried the steps I descibed above, but to no luck. looking into the Console app of OS X I found the following error messages;

2/2/12 4:20:57.153  com.apple.SystemUIServer.agent: No images found for wid 53
2/2/12 4:20:57.153  com.apple.SystemUIServer.agent: screencapture could not capture window 35
2/2/12 4:21:25.511  com.apple.SystemUIServer.agent: No images found for wid 32
2/2/12 4:21:25.511  com.apple.SystemUIServer.agent: screencapture could not capture window 20
2/2/12 4:21:45.773  com.apple.SystemUIServer.agent: No images found for wid 282
2/2/12 4:21:45.773  com.apple.SystemUIServer.agent: screencapture could not capture window 11a

Through sheer luck, I bumped into the solution; while I was trying to solve this mystery, I needed more desktop real-estate. So I switched on my second monitor (connected through DisplayPort). After a couple of minutes I tried the capture again, and it worked. Up till that point, I only have been playing with the plist files from my laptop or server and copying them to my iMac..... **FLASH**

Looks like that when the screen settings are set to Mirroring, and the external monitor is switched off, you run into this weird behavior. Rebooting with no monitor attached (switching it off doesn't seem to do the trick) also solves the problem, but introduces the one where you're missing screen real-estate....

Nikon Scan 4 and Snow Leopard

My dad switched to an iMac a couple of weeks ago. He came from a Windows environment with lots of periferals (RF Mouse, Bluetooth dongle, HP flatbed Scanner, Espon printer, Nikon CoolScan V, HP PDA, etc.). So the challenge was to migrate as many periferals as possible.

Thankfully, most of them worked. Even the old Nikon CoolScan V film scanner worked with the supplied Nikon Scan 4 software, until last Sunday. For some reason the application crashes with a message that the preferences file can't be read (Is another instance of Nikon Scan 4 running??).

It seemed that the Nikon app wasn't shut down properly on one occasion and a lock file was left in the preferences. Removing the lock file solved the issue.
The lock file is located at the following location:

~/Library/Preferences/Nikon/Nikon Scan 4 Prefs.lock

Sidenote: Weird that relatively old propriatary software like the Nikon Scan 4 software works fine, but that more recent (Nikon) software needs special updates to keep working under Snow Leopard. Was Nikon Scan 4 written by people who understand what they were doing (OS sub-version independent)? Or is this just luck?

Update on Friday, November 20, 2009 at 21:30 by Willem

Eventhough the Nikon Scan software works in Snow Leopard (OSX 10.6), Nikon abandonned the support for Nikon Scan 4 a while back. Alternatively you could use SilverFast from LaserSoft (commercial software).

Deleting Locked Files in OSX

During the migration of the data on my dad's (*cough*) Windows computer to his new iMac, we ran into lot's of locked files. Usually you get the information on a specific file (⌘ + i) and deselect the 'Locked' option in the 'General' part. It's basically impossible to remove all the locks by hand, so I needed a quicker way to remove these locks.

It seems that there's a command available in Terminal to do this. The following command removed the Locks from all the files in the current directory AND all the sub-directories.

chflags -R nouchg *

More info on the chflags command can be found in the Terminal by typing man chflags, or by visiting this page.

The cause of the locked files in my case was that we copied the data from a read-only network share (to prevent that information might get lost in copy/move actions during the migration). Reading from read-only media results in locked files (or so it seems).