Transaction data already exists. See long text

What causes this issue?

You want to change the <DS:DE.FKBER>functional area</> in the master
data even though postings with this functional area have already been
made. If you change the functional area, future postings are made using
the new functional area. The change made to the functional area has <LS>
no</> effect on postings that have already been made.

System Response

It is not possible to change the functional area if this message is an
error message.

How to fix this error?

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Procedure for System Administrators

<ZH>Caution</>
Changes to the functional area can lead to undesired effects if
documents are reversed: If, subsequent to the functional area being
changed, documents posted prior to this change are then reversed, the
reversal document may in some cases be posted under the new functional
area.
The system response is different in on premise and cloud installed
bases:
In <zh>on premise</> system installed bases, meaning non-cloud, the
following applies:
In the standard system, the message appears as an error message: After
the functional area has been changed in the master data within a current
fiscal year, issues may arise when performing certain period-end closing
activities for Controlling, for example, during cumulated assessment;
see SAP Note 244167.
If you want to change the functional area anyway, you can change the
message type of this message. To do so, in Customizing for Controlling
choose <LS>General Controlling -> Change Message Control</>. The <LS>
application area</> is FH, the <LS>message number</> is 600.
If you want to change the functional area in documents that have already
been posted, you can make a manual transfer posting for the posted
documents.
This message appears when a functional area is changed in different
master data, such as cost centers, internal orders, or G/L accounts. If
you change or switch off the message type for this message irrespective
of the user name, this change takes effect in all programs in which the
message is used.
Furthermore, if you change the message type for this message to Warning
or Information, this can unfortunately lead to the message not being
sent at all (due to technical reasons). This is the case, for example,
if you change the functional area in some master data in the project
system.
For this reason, we recommend the following:
Change the message type for specific users only.
Once the functional area has been changed, reset the message type to
error (<LS>E</>).
In <zh>cloud</> systems, this message usually appears as a warning for
the following reasons:
RESET N2
In cloud systems, customers cannot change the message type.
The potentially problematic period-end closing activities mentioned in
SAP Note 2442167, for example, cumulated assessment, are not available.

Error message extract from SAP system. Copyright SAP SE.