Hi Galina,
Debug info: Incorrect string value: '\xD0\x93\xD0\xBB\xD0\xB0...' for column 'value' at row 1
UPDATE mdl_config SET value = ? WHERE name = ?
This error is typical of a problem with the character encoding of your moodle database.
See these discussions:
http://moodle.org/mod/forum/discuss.php?d=208161
http://moodle.org/mod/forum/discuss.php?d=169338
Joseph