Xcode 4.1 fatal error: stdlib modified since the precompiled header was built

Building an iPhone app, using:

• Xcode 4.1
• Base SDK iOS 4.3
• Apple LLVM Compiler 2.1

I have started getting the following error:

> fatal error: file > '/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/../lib/clang/2.1/include/stdint.h' > has been modified since the precompiled header was built

I have tried reinstalling Xcode and OS X - no luck. What's causing this?

First try a clean build via the Product -> Clean menu (as of XCode 4.6.2).

If that still doesn't work then open the Organizer (from the menu select Window->Organizer). Once the Organizer is open, select Projects from the toolbar at the top of the window. On the left is a list of projects, select the one you are having a problem with.

The details panel (to the right of the list) will display the project name, location, status. The row beneath that shows where the Derived Data is located. Click the Delete... button the far right. A dialog will appear, click Delete.

You can also manually delete the Derived Data:

~/Library/Developer/Xcode/DerivedData/{project name + gobly-gook}

This directory contains built products and indexes for the project. It is OK to delete it because it only contains items generated by Xcode. Xcode will regenerate everything next time the project is opened.

I was able to fix it in a much easier way, by simply choosing Product > Clean, then Product > Build from the Xcode menubar.

Deleting the DerivedData folder did not work for me when Archiving.

I had to look at Build Settings - Build Locations - Precompiled Header Cache Path and delete that folder.

For me that was:

/var/folders/_w/t0mj70hd1439tqgxff7_mtt00000gn/C/com.apple.Xcode.501/SharedPrecompiledHeaders

I thought I would add a separate answer rather than a comment to Cryptognome's answer, because it is in fact a different solution when the issue comes from running xcodebuild. Like Cryptognome, I had the error come up with the command-line tool xcodebuild. As an alternative to manually going into the /var subfolders, I found that I could set my own cache for the shared PCH, which you can do by setting the environment variable SHARED_PRECOMPS_DIR, e.g as follows

xcodebuild -target Foo -configuration Release SHARED_PRECOMPS_DIR=/tmp/foo/SharedPCH

This way, I never get the error in automatic builds.

Note in the above command, I would also typically set the OBJROOT and SYMROOT env var to build also in /tmp. At the end, I clean things up.

The xcodebuild command line tool sometimes fails with this error. This happened to me when I synched an svn workspace to an earlier build. The xcodebuild tool keeps its precompiled headers in the folder Ants mentioned:

/var/folders/... scrambled eggs .../-Caches-/com.apple.Xcode.503/SharedPrecompiledHeaders/

You have to look in the build command itself to see the actual folder name (-include /var/...), but it may be using several if you're building for different architectures (arm6, arm7, simulator, e.g.) So if you're having this problem with a command line build, just delete everything in /var/.../SharedPrecompiledHeaders.

Remove the contents for the Simulator by iOS Simulator > Reset Content and Settings... and hit Rest. This will remove any existing pre-compiled instances of the headers and resources. This worked for me

Solution:

1)Product->Clean

2)Product->Build

Error Type:

a kind of Build error

One of the causes:

one might have changed the framework file. This sometimes happens when a change is made to a framework that another framework depends upon. The precompiled header cache gets out of sync, and Xcode is unable to compile the given project.

One of the Scenarios:

one might have chosen Jump To Definition and did some change after selecting a framework control.

I was able to get rid of this error simply by cleaning (command+shift+K) and rebuilding.

I tried above all but no use. Finally I deleted Xcode and re installed again. Now it is working fine..

Xcode->delete->install again

It might help some one...

I had this error on cordova when I ran : cordova run ios

fatal error: file '/Users/.../cordova/platforms/ios/CordovaLib/CordovaLib_Prefix.pch' has been modified since the precompiled header
  '/var/folders/gb/3cf6hy4x7z3d7hprls6xmd0m0000gr/C/com.apple.DeveloperTools/6.0-6A313/Xcode/SharedPrecompiledHeaders/CordovaLib_Prefix-bfgesbulnxtdepfwgniffeysypgv/CordovaLib_Prefix.pch.pch' was built
note: please rebuild precompiled header
  '/var/folders/gb/3cf6hy4x7z3d7hprls6xmd0m0000gr/C/com.apple.DeveloperTools/6.0-6A313/Xcode/SharedPrecompiledHeaders/CordovaLib_Prefix-bfgesbulnxtdepfwgniffeysypgv/CordovaLib_Prefix.pch.pch'
1 error generated.

** BUILD FAILED **    

The following build commands failed:
    CompileC build/CordovaLib.build/Debug-iphoneos/CordovaLib.build/Objects-normal/armv7/NSDictionary+Extensions.o Classes/NSDictionary+Extensions.m normal armv7 objective-c com.apple.compilers.llvm.clang.1_0.compiler
    CompileC build/CordovaLib.build/Debug-iphoneos/CordovaLib.build/Objects-normal/armv7/CDVInvokedUrlCommand.o Classes/CDVInvokedUrlCommand.m normal armv7 objective-c com.apple.compilers.llvm.clang.1_0.compiler

I tried with clean and build but doesn't work, finaly I removed the folder '/var/folders/gb/3cf6hy4x7z3d7hprls6xmd0m0000gr/C/com.apple.DeveloperTools/6.0-6A313/Xcode' and works! This tip, may be help others

Clean ways are not working for me, eventually I solved this issue by reinstall XCode.