can+have+p.p vs. could+have+p.p

Hello there;

would anyone kindly explain the difference between can+have+pp and could+have+pp
"she can't have missed out on the program."
"she couldn't have missed out on the program."

Depending on context (as always), both are possible.

Note that we don't normally use 'can have + pp' in the positive. So you can use "could have + pp".
With the negative, "couldn't have" implies some sort of conditionality. In many cases, there's no real difference.