Why am I getting an error "Failed to locate or generate matching signing assets" in Xcode 6?

In keychain access, -> Show Expired Certificates, then in your login keychain click on expired certificate and delete it. I also had the same expired certificate in my System keychain, so I deleted it from there too.

-> After deleting the expired cert from the login and System keychains,download certificate from below link and open with keychain.

Download https://developer.apple.com/certificationauthority/AppleWWDRCA.cer and add it to Keychain access > certificates (which expires on 2023)

this solved my problem

I edited distribution profile and downloaded it again, restarted xcode and it worked.

I have been searching answer for this problem past 6 hours. Nothing is satisfactory. As no one knows why this is happening. Following is way to generate .ipa via command line. If that works I will update here tomorrow.

xcodebuild -exportArchive -archivePath $projectname.xcarchive -exportPath $projectname -exportFormat ipa -exportProvisioningProfile "Provisioning Profile Name"

Note : The "Provisioning Profile Name" is the name specified in the name field of the certificate (viewable from developer.apple.com).

This will create .ipa.

credit goes to Orginal author here

This trick worked for me.