Following termination of guardianship, the court should have proceeded under section 388, but the error was harmless. In 2013, father’s reunification services were terminated and the minor was appointed a legal guardian. In 2016, the Agency filed a new petition under section 300, seeking to terminate the guardianship and set a 366.26 hearing. Father sought writ review, contending that the Agency erred when it filed a new section 300 petition instead of a petition under section 388 to terminate the guardianship. Father contended the error was prejudicial because it denied him the opportunity to seek reunification services at a review hearing following termination of the guardianship. The appellate court denied the petition. The Agency should have proceeded under section 388, not section 300. However, the court is required to consider further efforts at reunification only if parents prove that such efforts would be the best alternative for the child. Here, any error was harmless because there was no reasonable probability the court would have ordered further services for father, given his prior failure to reunify and his ongoing substance abuse.