Failed to launch simulated application: Unknown error

Question

• OS X 10.5.7 (genuine Mac)
• Xcode 3.1.3
• iPhone SDK 3.0

When I try to execute my iPhone application in simulator, I get the dreaded error

Answer 1

I believe that ultimately there are a spectrum of issues at play here. Some may be resolved by clean & rebuild, deleting preferences, etc.

None of these help resolve my issue.

I discovered that I had added some 3rd party code to my app that contained 1.) XIB files for their sample app and 2.) an info.plist file both of which erroneously had been added to my target.

Removing the XIB did not resolve the issue, but removing the info.plist file did.

Check your targets carefully and ensure that the assets that are being built and bundled are in fact needed.

Answer 2

I was getting this problem when I had my Info.plist file set to export to the target. You might want to check that, de-selecting that option fixed the problem for me.

Answer 3

I had a similar issue with a different solution: some of my .xib files had a deployment target (2.0) that was no longer installed on my machine.

The solution was to open the xibs in Interface Builder, do cmd-opt-I to get the project info for each one, and make sure the deployment and development targets were set to correct versions.

I then did cmd-shift-K to clean the project in XCode, rebuilt, deployed, and everything seems to work fine.

Answer 4

I had the same problem. Turned out the Info.plist was "missing" and had to be explicitly declared in the project settings. For some reason using the default name wasn't enough.

Answer 5

I just encountered similar error after cleaning up our XCode projects and updated them to use XCode config files. It occured only to one of our iPhone application targets, not all of them.

XCode said

Error from Debugger: Failed to launch simulated application: Unknown error.

In Console, only information was following two lines:

30.9.2009 14.31.19 com.apple.launchd[99] (com.apple.iPhoneSimulator:com.apple.dataaccess.dataaccessd) Path monitoring failed on "/var/mobile/Library/Preferences": No such file or directory 
30.9.2009 14.31.19 Xcode[13827] Error launching simulated application: Error Domain=DTiPhoneSimulatorErrorDomain Code=1 UserInfo=0x389db50 "Unknown error." 

It turned out that I had accidentally deleted Info.list file build setting from the target and neither XCode nor iPhone simulator could emit any useful error message about that. Adding a build setting again fixed the problem.

Answer 6

Another reason for such an error message: a number in the executable file name (set in the projet plist file under "Executable file" key). The solution was to remove any number there, remove the application in the simulator, quit and relaunch xcode, rebuild, and tada, it's that simple :-(