Manually grading any question fails with an "Error writing to database" message if you use the comma "," as a decimal separator.

The situation may pass unnoticed in installations using languages that have the dot as the decimal separator, but it becomes obvious in other languages like catalan or spanish, where the comma is used. Situation is worsened by the fact that Moodle fills out the box with a default value (the current mark), using the same decimal separator convention as the current language, misleading the user.

User can work around this bug by always entering numbers using the dot as the decimal separator.