Posting not possible, more than 9999 items would have to be created

Message type: E = Error

Message class: >0 - Contract A/R and A/P: Reserved message class

Message number: 399

Message text: Posting not possible, more than 9999 items would have to be created

What causes this issue?

In order to execute the required posting, you would have to create a
document with more than 9999 business partner items. However, documents
can only cover a maximum of 9999 business partner items.

System Response

Error message, you cannot execute the required posting.

How to fix this error?

This problem occurs for example, during the clearing of collective
bills if the receivables are budget billing requests. If several
collective bills are cleared, the number of original receivables, and
thereby the budget billing items to be created can exceed 9999.
You should therefore carry out clearing several times, each time
considering only so many collective bills that the total number of
items does not exceed 9999.