Hi,
While generate .ipa file using my development Apple certificate the build failed with general error ("Oh no! It wasn't supposed to happen but the build failed.....")
While generate the same project to android all working as expected. I exported Xcodeproject on my MAC and the build worked fine.
For to generate file Certificate p12 on KeyChan -- My certificates and I selected the certificate distribution with privatekey and export to p12.
For the Provisioning Porfile I uploaded a file that I downloaded for site developper IOS with extension mobileprovision.
Could you exposed the build logs?