Core issue
This problem occurs when the username is still stuck in the database .
This issue is documented in Cisco bug ID CSCsc91075.
Resolution
The only workaround is to download and upgrade the Cisco IOS Software Release to one of these versions:
- 12.4(6.6)
- 12.2(18)SXF4
- 12.2(18.10.6)SX3a
- 12.2(18.10.20)SX
- 12.2(32.08.02)SR
- 12.4(6.6)T