What does "POST token is missing or incorrect" mean?

The web works by changing data between your internet browser and the server. The mechanism for recognizing multiple requests from the same browser is called a session. 

This error may occur if there are session changes between opening the page and submitting a form from that page. In simple terms, this may be caused by submitting changes in an open tab whilst you may have logged out on the other tabs.

It is also possible when a laptop or computer has gone to sleep, and during that time the user session expires. When the computer wakes up, a user may try to submit the unfinished work, but the session will no longer be valid.

In most cases, clicking "Back to Previous Page" button in your browser should suffice, and even retain your form data.

This is a security feature to prevent cross-site request forgery.

If going back does not work, refresh the page or manually log out of the Intranet and clear your browser cache, then log back in to test.