I recently upgraded Moodle from 1.9 to 2.0.2 (Build: 20110221. I have noticed a number of "Error writing to database" errors when creating and deleting new courses. The stange thing is that it seems like the courses have been created and seem to function normally. I have now just upgraded to 2.1, but the problem persists.

I turned on debugging and I get this when I delete a course:

Deleting atest
Deleted - Grades, Items, Categories
Deleted - Outcomes
Deleted - Scales
Deleted - Settings
Deleted - Letters
Deleted 0 x assignment
Deleted 0 x chat
Deleted 0 x choice
Deleted 0 x forum
Deleted 0 x glossary
Deleted 0 x label
Deleted 0 x lesson
Deleted 0 x quiz
Deleted 0 x resource
Deleted 0 x scorm
Deleted 0 x survey
Deleted 0 x wiki
Deleted 0 x workshop
Deleted 0 x feedback
Deleted 0 x data
Deleted 0 x folder
Deleted 0 x imscp
Deleted 0 x page
Deleted 0 x url
Deleted groupings
Deleted groupings_groups
Deleted groups_members
Deleted groups
Deleted - course tags

Error writing to database

More information about this error
Debug info: Duplicate entry '5-200001' for key 2
UPDATE mdl_course
SET sortorder = sortorder + 1
WHERE category = ?
[array (
0 => '5',
)]
Stack trace:

line 396 of /lib/dml/moodle_database.php: dml_write_exception thrown
line 707 of /lib/dml/mysqli_native_moodle_database.php: call to moodle_database->query_end()
line 1095 of /lib/datalib.php: call to mysqli_native_moodle_database->execute()
line 74 of /course/delete.php: call to fix_course_sortorder()

and this when I create courses:

Debug info: Duplicate entry '4-250000' for key 2
UPDATE mdl_course
SET sortorder = ((sortorder) % (10000)) + ?
WHERE category = ?
[array (
0 => '250000',
1 => '4',
)]
Stack trace:

line 394 of /lib/dml/moodle_database.php: dml_write_exception thrown
line 707 of /lib/dml/mysqli_native_moodle_database.php: call to moodle_database->query_end()
line 1066 of /lib/datalib.php: call to mysqli_native_moodle_database->execute()
line 3712 of /course/lib.php: call to fix_course_sortorder()
line 111 of /course/edit.php: call to create_course()