How to solve run time error

[Robert (swelteringEngine)]

1. Please do not mention so much users, they are likely read the new topics.

2. Please search before posting.

Run time error - unable to add window -- token android-os.blinderProxy@f69eef9 is not valid; is your activity running?

Run time error - unable to add window – token android-os.blinderProxy@f69eef9 is not valid; is your activity running?? please help me how i can resole it

How do you switch screens?