If the I30 error code appears, there is a pump problem. Try to reset your device by either disconnecting it from the mains or shutting off your household circuit breaker for about 30 minutes. Reconnect the machine and run a cycle. If the problem persists, do the steps described below.
This may happen when a collection pan at the bottom is filled with water. The high level raises a float, which activates an anti-flood function. If that is the case, take steps to drain water from your unit. You can tip your dishwasher and empty the pan. The error will disappear, at least for a while, until the pan fills again. If it does, there is a leak, which you should address right now unless you want to do it over and over again.
A leak can be hard to find. First, you should check the door rubber gasket and ensure it does not let water through. If you cannot find the leak, but the problem comes back from time to time, use professional technical help.