During database backup via database manager in  Odoo V7, I suddenly get the following nasty error:

SyntaxError: JSON.parse: unexpected character at line 1 column 1 of the JSON data

Database backup without database manager but directly with pg_dump is successful and dump file is okay (I succeeded in reimporting it).

Just want to understand, why it can not be done via database manager any more. Could anybody help me with this issue and tell me what to do to be able to backup database via database manager?