You can link only one central house bank account to a bank account.

What causes this issue?

You have tried to link more than one central house bank account to this
bank account. However, for each bank account, you should link only one
house bank account with the connectivity ID category <LS>Central System:
House Bank Account</>. This way, the linked central house bank account
serves as the unique representation of the bank account in payment
transactions.

System Response

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

How to fix this error?

In the <LS>Manage Bank Accounts</> app, open the bank account and then
go to the <LS>House Bank Account Connectivity </>tab. Make sure that
there is only house bank account linked with the connectivity ID
category <LS>Central System: House Bank Account</>.

Procedure for System Administrators

IF &[SWITCH]S4H_DOCU_CLOUD& = 'X'.
If you want to enable linking to multiple house bank accounts, you can
do so by changing the error message <AB>FCLM_BAM_MAINT537</> to a
warning message or switching it off using the Configuration step
<LS>Change Message Control</>.
You can find the configuration step in the <LS>Manage Your Solution
</>app under <LS>Manage Your Solution -> Configure Your Solution</> ->
<LS>Finance -> General Settings.</>
ELSE.
If you want to enable linking to multiple house bank accounts, you can
do so by changing the error message <AB>FCLM_BAM_MAINT537</> to a
warning message or switching it off using the Customizing activity
<DS:SIMG.FCLM_BAM_MSG_CTRL>Change Message Control</>. You can find the
Customizing activity under <LS>Financial Supply Chain Management</> ->
<LS>Cash and Liquidity Management </>-> <LS>Bank Account Management
</>-> <LS>Basic Settings</>.
ENDIF.

Error message extract from SAP system. Copyright SAP SE.