G/L account & cannot be created as a cost element

What causes this issue?

When maintaining the posting rules for passing on
<GL:results_analysis_data>results analysis data</> to Financial
Accounting, you entered a G/L account that is defined as a primary
<GL:cost_element>cost element</> in cost and revenue element
accounting. This is not allowed. You must enter a G/L account in the
posting rules that is not defined as a cost element.

System Response

The entry invalid.

How to fix this error?

You have the following options:
Enter a G/L account for which no cost element is specified in Cost and
Revenue Element Accounting.
You can change the message type with user-defined error management
(transaction OPR4_KKA). What should be observed when you enter a G/L
account in a posting rule that is defined as a primary cost element in
Cost and Revenue Element Accounting? You need to define a CO account
assignment so that the posting defined in the posting rule can be
executed. You do this with transaction OKB9 (default account
assignment) or OKC9 (substitution), or using the default account
assignment in the cost element master.

Error message extract from SAP system. Copyright SAP SE.