FileMerge error message when used with Git difftool

Question

I use FileMerge as the difftool tool for Git. Recently, I started receiving a weird error message:

Unable to load platform at path /Applications/Xcode.app/Contents/
   Developer/Platforms/iPhoneOS.platform

FileMerge still performs the diff just fine (although it takes a bit longer to load). Any idea what's causing this, and how to fix it?

Answer 1

I had exactly the same problem while using FileMerge as a diff tool for svnX. The following command solved my problem:

sudo xcode-select -switch /Applications/Xcode.app/Contents/Developer/

That's all.

Answer 2

To expand on user3761183's answer, after a bit of googling I ran:

sudo plutil -convert xml1 /Applications/Xcode.app/Contents/Developer/Platforms/*.platform/Info.plist

That got rid of all the Unable to load platform at path /Applications/Xcode.app/Contents/Developer/Platforms/AppleTVOS.platform errors. I'm still getting errors about:

Couldn't load '/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/Library/Xcode/Specifications/Core Build System.xcspec'. Reason: Error Domain=NSCocoaErrorDomain Code=3840 "Unexpected character b at line 1" UserInfo={NSDebugDescription=Unexpected character b at line 1, kCFPropertyListOldStyleParsingError=Error Domain=NSCocoaErrorDomain Code=3840 "Unexpected ';' or '=' after key at line 1" UserInfo={NSDebugDescription=Unexpected ';' or '=' after key at line 1}}.

But I was getting them originally too, so if you aren't then the above command should solve your problems.

EDIT: removed comment about Install addtional required components that did nothing. Next guess is reinstalling XCode as Jonathan F suggests.

FWIW I tried sudo xcode-select -switch /Applications/Xcode.app/Contents/Developer/ already and that did nothing too.