The message output of the error already tells it doesn't it?
Think of it this way: You're working at McDonalds, packed a burger and packed it to the shelter (queueing burgers) for the cashiers - now after that one specific burger has already been sold and the customer started eating it, it's not really possible to do any adjustments to it is it?
A very good explanation, what could cause that issue and how to prevent it:
https://stackoverflow.com/questions/...t-error-in-php
Hope I was able to help out!