how to resolve it new here
It seems the issue is the symbol MPHASIS. The dataset you have chosen tracks NSE F&O stocks only. MPHASIS entered this recently (in March 2021). Price data will be missing before this data.
The solution is to choose your backtest start date after this date + the look back dates in your strategy (which is 10 busiess days). Please try out a starting date on or after 15th of March 2021. If that does not solve your issue, please drop a line to blueshift-support@quantinsti.com