Hi Wenyu,
Open the Task Manager in your PC and find Studio pro and click end task.
Then try opening the app again.
Check if you have another instance of Mendix Studio open, which has your project 'Tablereservation' open.
If so, click "Cancel" and go to that other instance of Studio.
If not, just click the button "Open anyway" and continue.
Background info: this happens if you previously had Mendix Studio open, with your project 'Tablereservation' and youclosed it hard, without giving Studio the option to clean up the project. Making it leave files ~-mpr.back and ~mpr.lock in the app-directory.
Is that by any chance your problem?https://www.youtube.com/watch?v=n9D4QVRJ1cY