Steps to reproduce:
* open [[ https://www.mediawiki.org/wiki/Manual:DatabaseUpdater.php | mw:Manual:DatabaseUpdater.php ]] for editing
* call up the template edit menu for the main template
* [[ https://www.mediawiki.org/w/index.php?title=Manual:DatabaseUpdater.php&diff=1427328&oldid=1186336 | modify ]]
The the browser starts sending requests to the visualeditoredit API and goes on repeating them forever. An example request (in cURL format) is P342. The response is always a badtoken error. The token does not change between requests.
The interface is unresponsive (none of the buttons work); Esc closes the save window but does not stop the request loop.
Could not reproduce, after reloading the page and redoing the edit it was saved successfully.
A lot of time passed between opening the page and starting to edit in VE, but not a lot of time between starting to edit and saving.