Error after Backtest - How to solve?

After the long BackTest process, I alway get this error message "Cannot open file ".......ex4" on the GBPUSD,H1

How to solve this problem ?

This happened just recently

Before I didn't meet this matter

You may have wrote the wrong name for the Custom Indicator you are using.
If you'll upload the code I could be of more help.

Not only 1 EA

Every EA has this same error

there must be something wrong that need modify in the Meta software, not the EA

anybody has any idea about this issue ?