MCA key &1 is not assigned to a position type

What causes this issue?

No MCA key is assigned to account. This means that further derivations
cannot be performed and it is not possible to derive a position account
for this account.

System Response

System terminates processing.

How to fix this error?

Maintain the MCA key in Customizing activity
<DS:SIMG.FI_GL_MD_FS00_DC>Edit G/L Account Centrally</>

Procedure for System Administrators

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

Error message extract from SAP system. Copyright SAP SE.