Internal error when implementing extension (see long text)

What causes this issue?

Call of <EX>GET_EXTENSION( )</> method for enhancement &V1& failed.
It tried to use an add-on or customer-specific enhancement that is not
implemented in your system.
To be able to determine the technical attributes of enhancement &V1&,
the <ZH>RECA_STORABLE_EXT</> Business Add-In has to supply the desired
information. However, this was not the case. In an implementation of
<ZH>RECA_STORABLE_EXT</>, the <EX>GET_OBJNAME_EXT( )</> method must
supply the required enhancement &V1&.
Below is example code for <EX>GET_OBJNAME_EXT( )</>:
CASE ID_OBJNAME_STD.
WHEN '...'.
APPEND '&V1&' TO CT_OBJNAME_EXT.
...
ENDCASE.
For more information, refer to the documentation for the
<ZH>RECA_STORABLE_EXT</> Business Add-In.
<DS:TRAN.SE18>Start BAdI Builder</>

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?

Contact your system administrator.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.