[Nektar-users] issue in my calculation

Thank you for reading my letter with your busy schedule. I'm an undergraduate so i'm not so skilled in CFD. Now i have a task that need me to use nektar++,but when i use the compressible solver to calculate it , the error 'vacuum is generated by given data' always comes up. I try to change my boundry conditions,but it doesn't work. Can you give me some suggestions? Looking forward to your reply!