Xcode 9: Could not attach to pid

问题:

I've been facing an issue (frequently) with the recent major release of the iOS application development tool - Xcode 9-beta.

It's showing me the following error frequently while running/debugging app in Simulator (iOS 11).

Could not attach to pid : “2370”
Ensure <project title> is not already running, and <system username> has permission to debug it.

Here is a snapshot for the same issue:

What would be permanent solution of this issue, as it's disturbing frequently?

回答1:

If issue is on OS Mojave and you are trying, like me to run tests on older Xcode version (lower than 10.0), make sure that in your scheme, when you select Test, Debug executable is disabled

You won't be able to debug tests from this point

回答2:

Still not a permanent solution, but I had to quit and restart XCode as the other solutions did not work for me.

回答3:

This worked for me:

Edit Scheme -> Info -> Executable -> Ask on launch

Credits to @nastya-gorban's answer here

Update

After spending a considerable time with examples on Apple bug report, they basically disregarded the issue as using manual certificates is not "expected".

Long story short, if you don't have a business account and hence multiple developers on the same account, you should be fine with using the automatic signing and should not see the issue.

If you do have a business account with multiple users (which I found it breaks automatic signing), this is their suggestion:

We suggest that you use automatic signing for your debug builds and manual signing for your distribution builds.

回答4:

Killing my simulator and then running it again from Xcode.

回答5:

I had this issue too. There seems to be an issue with having two Xcode version installed at the same time. (9.4.1 and 10.0 Beta)

It works with the beta, but not with the stable version. Everything is set to the tools of the Xcode 9.4.1 stable version. I can only run my unit tests with the beta.

After removing the beta, it worked with the stable version.

回答6:

delete derived data and clean the project, wait until processing is complete, this may take some time. The idea is to give some processing time. Works fine after that

回答7:

I have been dealing with this issue for days. I have been able to build but not launch on Simulator, and I get the same "pid:.." error message.

I am using: - Xcode v9.2 - Swift 3.2 - Building for iOS

The things that I tried that DID NOT WORK were:

restarting the computer; deleting content and settings (of Simulator, I do not have "reset"); uninstalling and reinstalling Xcode; changing "Deployment Target"; changing the device in the simulator's Hardware->Manage Device; deleting Derived Data, Cleaning and Building, or just waiting...forever.

What WORKED was as @Rajasekhar mentioned:

• checked out the Keychain certificates.
• deleted the exiting ones by right clicking (they'd passed expiration)
• and unchecked "automatically manage signing" in Targets->General

After that it successfully launched in Simulator. I don't know if the issue will come back but hopefully this works.

回答8:

I too faced the same issue, I was trying to run the test cases with older version of xcode (9.4 in my case).

Disabling Debug Executable worked.

回答9:

This seems to be a temporary issue when you are trying to build too fast after a build has started. Try stopping and running the project again.

回答10:

This is the issue with the untrusted certificates in key-chain access, please remove such a type of certificates and re-build again.

回答11:

I hate to add more noise to this, but for me, the answer is to, nonsensically, use sudo.

Run normally, Xcode 9.4.1 (9F2000) and Xcode 10.0 beta 4 (10L213o) both failed to attach to my app after multiple tries, giving the error quoted in the original post.

What worked was to run Xcode (9.4) with sudo,

sudo /Applications/Xcode.app/Contents/MacOS/Xcode

I don't see why sudo is necessary. The Cocoa app to which I am attaching is a Debug build that I just built in Xcode 9.4.1 and dragged into /Applications. It is not codesigned. Posix permissions on the .app, its Contents, its MacOS, and the executable are all octal 755. Owner is me. It works fine if I leave it in the Build folder, build and debug in the normal way.

The problem is apparently with lldb. I also tried using lldb (lldb-902.0.79.7) from the command line. I got the same result. It works only with sudo. Without sudo,

error: attach failed: unable to attach

回答12:

(most likely solution) 1. Simulator-> Hardware-> Erase all contents and Settings

(less likely solution) 2. keychain-> upper right lock-> unlock and lock again (or the other way around)

回答13:

This happens on my machine, when I set the 'new build system' Go to menu file=>workspace settings and set Build System to "Standard".