ORA-01861: literal does not match format string

Question

Remove the TO_DATE in the WHERE clause

TO_DATE (alarm_datetime,'DD.MM.YYYY HH24:MI:SS')

and change the code to

alarm_datetime

The error comes from to_date conversion of a date column.

Added Explanation: Oracle converts your alarm_datetime into a string using its nls depended date format. After this it calls to_date with your provided date mask. This throws the exception.

The error means that you tried to enter a literal with a format string, but the length of the format string was not the same length as the literal.

One of these formats is incorrect:

TO_CHAR(t.alarm_datetime, 'YYYY-MM-DD HH24:MI:SS')
TO_DATE(alarm_datetime, 'DD.MM.YYYY HH24:MI:SS')

SELECT alarm_id
,definition_description
,element_id
,TO_CHAR (alarm_datetime, 'YYYY-MM-DD HH24:MI:SS')
,severity
, problem_text
,status 
FROM aircom.alarms 
WHERE status = 1 
    AND TO_char (alarm_datetime,'DD.MM.YYYY HH24:MI:SS') > TO_DATE ('07.09.2008  09:43:00', 'DD.MM.YYYY HH24:MI:SS') 
ORDER BY ALARM_DATETIME DESC 

Just before executing the query: alter session set NLS_DATE_FORMAT = "DD.MM.YYYY HH24:MI:SS"; or whichever format you are giving the information to the date function. This should fix the ORA error

A simple view like this was giving me the ORA-01861 error when executed from Entity Framework:

create view myview as 
select * from x where x.initialDate >= '01FEB2021'

Just did something like this to fix it:

create view myview as 
select * from x where x.initialDate >= TO_DATE('2021-02-01', 'YYYY-MM-DD')

I think the problem is EF date configuration is not the same as Oracle's.