App Crashes On Start

What should I do if iCertifi crashes on start up

*** Please update to latest iOS version ***

If iCertifi crashes after updating it to the latest release (usually right after you launch it), it's possible you're experiencing a bug in certain versions of iOS, the operating system on all iPhone, iPods and iPads.

First of all try restarting the device by holding the power button and home button together until the device restarts. Why do you need to do this? During the update process, it's possible on certain versions of iOS that the app is not perfectly cleaned up by the system, not allowing the newly installed version to start correctly. A hard reboot fixes this.
If that does not work deleting and reinstalling iCertifi will sort the issue.  More Information on reinstalling iCertifi and retrieving certificates after reinstall can be found here