missing ios development signing identity for (null)

Question

when i try to generate ipa file, i am getting this error. Not able to solve.Please help me out to resolve this error:

i have own account , in my key chain a

Answer 1

Here's statement from Apple.

Thanks for bringing this to the attention of the community and apologies for the issues you’ve been having. This issue stems from having a copy of the expired WWDR Intermediate certificate in both your System and Login keychains. To resolve the issue, you should first download and install the new WWDR intermediate certificate (by double-clicking on the file). Next, in the Keychain Access application, select the System keychain. Make sure to select “Show Expired Certificates” in the View menu and then delete the expired version of the Apple Worldwide Developer Relations Certificate Authority Intermediate certificate (expired on February 14, 2016). Your certificates should now appear as valid in Keychain Access and be available to Xcode for submissions to the App Store.

https://forums.developer.apple.com/thread/37208

1. Download https://developer.apple.com/certificationauthority/AppleWWDRCA.cer and double-click to install to Keychain.
2. Select "View" -> "Show Expired Certificates" in Keychain app.
3. Remove Apple Worldwide Developer Relations Certificate Authority certificates from "login" tab and "System" tab in Keychain app.

Ensure the new downloaded cert is in both login and system Default to only system tab will still give error.**