Gov. Jerry Brown and California’s legislative leaders won plaudits from opponents of America’s pervasive gun violence in 2016 when they banned the sale of semiautomatic rifles with “bullet buttons” that make it easy to quickly unload — and then load — ammunition magazines. Owners of the weapons that were purchased before the ban took effect last year were required to register their weapons with the state Department of Justice by June 30. But a new lawsuit filed by several gun groups contends that the computer system to register the weapons wasn’t working in the days leading up to the deadline. This puts tens of thousands of Californians at risk of felony charges for transporting an unregistered assault weapon, with prison sentences possible of up to eight years. The gun groups say the failure of the registry system should have been anticipated by state Attorney General Xavier Becerra because of problems well before the deadline neared, and that the Department of Justice reacted indifferently to reports of online registration snags. These claims are difficult to verify. But at the least, it’s a bad look for state government to botch the rollout of a reasonable gun control law. Gun owners who wanted to register but haven’t been able to shouldn’t face consequences. It’s another story for state bureaucrats who had plenty of advance notice and a clear deadline but didn’t get their jobs done.