Issue "Error 404" when upgrade AIX 5300-05-CSP-0000 to AIX (5300-09-02-0849)

Please read my issue!
My old server using:
- AIX system operating (5300-05-CSP-0000)
- WebSphere 6.1.0.21 (Fix Pack 21)
After I've upgraded version AIX
- AIX system operating (5300-09-02-0849)
- WebSphere 6.1.0.21 (Fix Pack 21)
I have 1 issue when I access home page:
"Error 404: java.security.PrivilegedActionException: javax.servlet.UnavailableException: CWPWC0029E: _ibmjsp.amstools._welcome "

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I need your help, please help me solve this issue!
Thank you so much!