Solution Import Error - The selected solution import file either does not exist or is invalid. Please select a file which was Exported from this system

We are trying to export a solution from 1 of our sandboxes and trying to import it to another sandbox instance but we are getting this kind of error saying "The selected solution import file either does not exist or is invalid. Please select a file which was Exported from this system"

Any idea on how to resolve this kind of issue. Thanks.