SAP Message UCF8051 - Automatic line items contain an error; posting is not possible

Diagnosis
Posting is not possible because the automatic line items contain errors.
The original and automatic line items are not consistent since thecharacteristics have been changed.

System Response
The document cannot be posted.

Procedure
Start the manual posting task again and re-enter the original lineitems. Then you can generate the automatic line items correctly,enabling the document to be posted.