I have migrated a database from Firebird 1.5 to 2.0. Now I have the
problem, that I have a table in which I can't update any data anymore.
It doesn't matter which col or which row, I always get the error:

This column cannot be updated because it is derived from an SQL function
or expression.
attempted update of read-only column.

Here's the DDL from the table:

create table COMMISSION_PERIODS (
CRID D_PK not null /* D_PK = INTEGER NOT NULL */,
CRNAME D_TEXT84_NOT_NULL_DE_DE not null collate DE_DE /*
D_TEXT84_NOT_NULL_DE_DE = VARCHAR(84) NOT NULL */,
CRSTART D_DATE_TODAY not null /* D_DATE_TODAY = DATE DEFAULT
'TODAY' NOT NULL */,
CREND D_DATE_TODAY not null /* D_DATE_TODAY = DATE DEFAULT
'TODAY' NOT NULL */,
CRACTIVE D_BOOLEAN_FALSE not null /* D_BOOLEAN_FALSE = SMALLINT
default 0 NOT NULL */
);

grant select, insert, update, delete on COMMISSION_PERIODS to public;

Any idea, what might be the reason for the error?

Regards

Guido