Diagnosis
Account 300000 is a profit and loss account. You assigned it to an object in cost accounting (for example, a cost center, order, project, or profitability segment).
In this case, a cost element category must exist for account 300000 in the determined controlling area ADD2.See transaction FS00, "Control Data" area.
Procedure
Define a cost element category for account 300000 and post again or delete the auxiliary account assignment to objects in cost accounting.
With profitability segment assignment, the error message is only displayed when account-based profitability analysis is activated. Here it may be a good idea to suppress the error message and ignore the account assignment during the posting. This is particularly the case when the posting is not only relevant for the result from the usual business activity, for example for interest from cross-company sales in a billing document. Such postings should not be taken into consideration in the profitability analysis. In order to do this, you can define the account 300000 in transaction FCO_COPA_EX_N (IMG -> Controlling -> General Controlling -> Account Assignment Logic -> Exceptions for Postings to Profitability Segment)
SOLUTION:
STEP 1: Go to T Code FS00 > Click on Edit and then under Control Data > Provide Cost Element Category and SAVE.
Thanks,
Adharsh K S