In an INSERT statement with a QUERY expression or in an UPDATE statement, the attempt was made to assign a character string to a column of data type CHAR. This character string was too long. The error message is returned for the first occurring value of excess length, not while analyzing the maximum column lengths.
Use SELECT... WHERE LENGTH (<column name>) > <unsigned_integer>to find out the rows that are too long. The length of the corresponding column can be increased by an ALTER TABLE statement.