I now have more information. The problem is with only one Time field in only one record. I isolated it by executing the following query, which produced the message in my original post:

select EffectiveTime from detf where PK_ID = 3654

However, when I try to set that field to NULL using the following query, I get the same error message, and the record is unchanged. How can I fix this short of deleting the entire record (if I can)?

update detf
set EffectiveTime = null
where pk_id = 3654

--- In firebird-support@yahoogroups.com, "homerjones1941" <homer@...> wrote:
>
> Using GBAK via IBExpert, I get the following message. I don't know how to fix it (or find it).
>
>
> Overflow occurred during data type conversion.
> conversion error from string "2013-04-11".
> gds_$receive failed.
>