by Matteo Scaramuccia.
Hi All,
just for the record, the issue is related to the value 0 instead of NULL for the default profile pages in the table my_pages.
It can be fixed by issuing (MySQL):
UPDATE `<database_name>`.`mdl_my_pages` SET `userid` = NULL WHERE `mdl_my_pages`.`userid` = 0;
HTH,
Matteo