Error List: Operation is not a valid due to the current state of object

while using config file in the test case workflow and click run it suddenly this error was shown. I do not how to clear the error
Can u anyone tell about the reason why its shown like this?

Can u plz anyone quick rply for the msg?

Can you show us the workflow. Is the Dictionary instantiated

Are u asking this @Che bro?

Can u plz rply @Che bro