This error means that the number of orders the strategy can execute on the chart has reached the max level of 9000. The limitation is enabled for our servers to work more efficiently.
The only alternative we can suggest is to plot a strategy with the fixed start date rather than from the beginning of the data history. You can add a comparison time > timestamp (2019, 01, 01, 09, 30) to the order condition, where time is the time of the current bar and timestamp() is the feature converting date and time to UNIX format. Please see the function description in Study Script Reference.
Here's an example:
longCondition = buying if (longCondition and time>timestamp(2019, 01, 01, 09, 30)) strategy.entry("Long", strategy.long) shortCondition = buying != true if (shortCondition and time>timestamp(2019, 01, 01, 09, 30)) strategy.entry("Short", strategy.short)