Error message:

“The content on this page has either been modified by another user, or you have already submitted modifications using this form. As a result, your changes cannot be saved.”

What does the error mean?

Note: Firstly, it’s important to note that this error message doesn’t denote a problem with your website, but more with the way the website is being accessed or used. The error is slightly misleading and prone to causing confusion (and is subject to review by Drupal maintainers) in that it displays in two possible scenarios, outlined below:
  • A user edits a content page, saves the changes and then uses the back button to navigate back to the editor page, makes additional changes, and saves.
  • Two different users attempt to edit the same content page at the same time. The second user to click the save button will receive this error.
The error message is suitable and appropriate for the second scenario but confusing for the first. Basically, it means that the page has been edited without following the proper steps to access the editor screen or the editor screen is being accessed simultaneously from two browser windows/tabs.

How to resolve the error:

On single user sites only access the editor screen in a single browser window or tab and don’t use the browsers “back” button to return to the editor screen (click the “Edit” tab/link if you want to make additional changes.  Following those steps will prevent this error from being displayed and save you having to make your changes repeatedly. On multi-user sites it’s a bit more complicated, but if you’re sure you’re following the steps above and still getting the error you might need to coordinate editing of content so that you’re not trying to make changes to a page that someone else is already editing.