When submitting an assignment the Save changes and Cancel buttons are not disabled when using the Chrome browser. According to MDL-38555 they should get disabled, and this is what happens with Firefox.

A customer who reported this sees this specifically with mod_assign but this may be a wider problem with form submission.

Browsers tested:

• Chrome 122.0.6261.95 on Microsoft Windows 10 (problem occurs)
• Chromium 122.0.6261.94 on Fedora Linux 37 (problem occurs)
• Firefox 123.0 on Microsoft Windows 10 (problem does not occur)
• Firefox 120.0.1 on Fedora Linux 37 (problem does not occur)

Steps to reproduce issue

1. Create a course and enrol a student.
2. Add an assignment to the course:
   1. Give it a name, for example, "Assignment 1".
   2. Submission types: "Online text"
   3. Feedback types: "Feedback comments"
3. As the student:
   1. Log into Moodle using the Chrome browser.
   2. Click on the assignment from the course page.
   3. Click Add submission.
   4. Type some text in the editor field ("test").
   5. Double click on Save changes.

Expected results

The Save changes button is disabled after the first click so the second click has no effect. The assignment is submitted with no error message.

Actual results

The error You have existing submission data. Please leave this page and try again. appears. This problem is more prone to happen when the submission is not immediate as the enabled Save changes button remains clickable by an impatient student (for example, with a large file upload, or where the submission is sent to a third party API for evaluation).