When creating new courses using the bulk "Upload Courses" feature, the new courses created are missing the default setting for the tile border colour.

Steps to replicate:

1. Create a new CSV (as per https://docs.moodle.org/31/en/Upload_courses) with the following fields specified: shortname, fullname, category_path, visible, format. Specify "grid" in the "format" field.
2. Upload the CSV in the Upload Courses tool
3. Set "Upload mode" to "Create new courses, or update existing ones"
4. Set "Update Mode" to "Update with CSV data and defaults" or "Update with CSV data only"
5. Upload the new course/courses by clicking "Preview" and then "Upload Courses"
6. Navigate to the new course
7. Edit the settings of the new course by going to Course Administration > Edit Settings
8. Under "Course format", check whether "Set the border colour" is set to the expected default (e.g. dddddd).

In my case, "Set the border colour" is set to 0, which throws an error asking users to "Please enter a valid RGB colour, six hexadecimal digits". I have found this error message has confused the majority of teachers who've encountered this issue.

As a workaround, I have directly edited any 0 values for "bordercolour" in the course_format_options table.