by Gerhard Bax.
I received the same error while installing a fresh Moodle 2.4.1 with new database. By default the MySQL database was set to utf_general_ci . Changed also to utf8_unicode_ci (recommended by Moodle), but still the same message. Tried also with an older version 2.3. of Moodle - same error! Had a year ago a running installation of Moodle 1.9 on that server at my webb-hotel without showing that error during installation.
Thanks for all help!