This also happens when the market is not closed, but no price quotes arrive during a bar period. There are two solutions. You can either generate bars even without quotes in the backtest, or you can skip bars without quotes in trade mode.

For the first solution, select a 24 hours asset such as EUR/USD before selecting the CFD. The first selected asset determines the bars.

For the second case, use the TimeFrame mechanism to skip bars when their price is identical to the previous bar or when the time is outside market hours.