Screen Capture Not Working -- "Unable to create type string"

Usually means your preferences are mucked up. Move the com.apple.screencapture.plist from /username/Library/Preferences/ folder onto the Desktop, restart, and try doing a screen capture. If that fixes things, delete the moved file. If not, report back.

Hi there, I had that problem too, to fix it I used a little app to change the format of the screen capture called ScreenMat 1.0, try it!

Regards

There are two places which can affect this error. I caused this problem for myself, by a typographical error when changing the defaults for screenshot from png to jpg, (I type jpb, which it didn't know). Check this with the following command:
defaults read com.apple.screencapture

It should either be empty, or have one or more variable assignments. Mine has location and type. The type line is the one which caused my problem. First step is to delete it, with the defaults command as follows:
defaults delete com.apple.screencapture type

Next, restart the process SystemUIServer with the following command:
killall SystemUIServer

Wait a minute or two for it to kill the process, and then spawn a new one. Then try your screen capture again.

If you still get the error, there could be a permissions problem or error in the file "/System/Library/CoreServices/SystemUIServer.app/Contents/Resources/English.lpr oj/Localizable.strings". There is a great article on changing this file at: http://www.macosxhints.com/article.php?story=20091228142521881

Remember that killall command above to restart the SystemUIServer after you make changes to this file as well.

Thanks SO much for posting this. I have had this screen capture problem on my MacBook ever since I bought it (about 15 months ago). It has persisted through OS updates, disk permissions repairs, and repeated searches of various support boards to find a solution. This ScreenMat app has finally made it possible for me to use the built-in screen capture solution (as opposed to having to use Grab and then use Preview to change tiffs to jpgs). Now I can capture the way I used to on my previous Macs and save to jpg to boot. THANK YOU! 🙂

Thanks!! I downloaded the screenmat app hoping it would work instead of me typing lines into terminal again and it worked!