This may be somewhat of an empirical approach but is worthwhile in the face of many commentators noting either “this worked for me” or “this didn’t work for me”. Firstly, the problem can lie in a number of locations, either your certificates (code signing identities) or your provisioning profiles. Identifying where the problem lies first before doing anything will save a lot of wasted effort. You will need to check in three places:

1. XCode
2. Keychain Access
3. The Developer Portal (Developer Members Centre)

OK, in XCode click on the Project (Above the Targets Heading), select Build Settings and scroll to ‘Code Signing’. Expand the ‘CODE_SIGNING_IDENTITY’ heading and you will see a bunch of identities (Debug, Release etc.) Each one of these will match up with a certificate in Keychain Access. Find the match and check the expiry date…if it has expired you will need to update it in the Developer Portal and download it. Check EVERY identity, not just the first one you find that has expired. Also, if it has expired you will need to regenerate any provisioning profile that used the expired certificate.
If no problems with the certificates, check the expiry date of all the Provisioning Profiles. Once again, if they have expired, they will need to be regenerated.

Once complete, repeat the same process for the TARGET you are trying to build for.

None of this worked? An expired certificate is lurking in one of your provisioning profiles. A sign that this might be the case is that when you click on a CODE_SIGNING_IDENTITY the identity is below Other… eg.

This is usually a sure sign that there is an expired certificate lurking about and that one of your profiles is using it.