Solution : https://service.sap.com/sap/support/notes/311113 (SAP Service marketplace login required)
Summary : 
      When attempting to enter a discontinuation or follow-up group in BOM updates, users may encounter termination with error A 29281, indicating 'Maximum low-level code 999 reached'. This note suggests consulting advance corrections to address the issue efficiently.
Key words : 
29281 'maximum low-level code 999 reached', bom update terminates, additional key words, discontinuation group, prerequisites solution, advance corrections
Related Notes : 
       
| 68792 | Collective note for low-level code / recursiveness |