No, the DNC did not rig the election in favor of Hillary Clinton because the public vote revealed that she was the most favored candidate. Sanders' protesters are making a claim that is invalid because they did not see their candidate thrive. The public vote determines the winning candidate and the results revealed that Clinton was the popular choice.
The DNC did not rig the election to favor Hillary Clinton. Although the DNC favored her, she raised funds on her own and campaigned successfully to beat back the surprisingly strong challenge from Bernie Sanders. Hacked e-mails show the DNC wanted Clinton to win, but there is no evidence of actually rigging the primary elections.
No, the election was not rigged. Though Bernie Sanders is not fond of closed primaries, he was well aware they would take place and even said himself, "That's not rigged." Furthermore, although Clinton fared better than Sanders in the closed primaries, she also won more open primaries than he did.
There were some unfair practices that certain staff members used to give Hillary an edge. But that does not mean the election was rigged. It was in fact, very close and hotly contested, which is going to lead to allegations of it being rigged, but makes it less likely that it actually was.