I am recreating a HEC-RAS model that works (dam failure, unsteady flow). I am using the original geometry data, have my dam breach data, flow hydrograph, mixed flow regime enabled, and time step the same as the original model. My hydrograph uses 6 minute intervals and starts at 14FEB2019 2400. I am running my model starting at 15FEB2019 0000 and stopping it before the data ends with time steps of 1 minute (same as original). I keep getting the error "Minimum error exceeds allowable tolerance at 14FEB2019 24:00:00" and "Simulation went unstable at 15FEB2019 00:01:00". Any ideas about how to fix this?