Root cause:

The MP 1.2.X sends the wrong POST request path when LDAP server forced to change user password using auto-detect certification as AAA server.
Solution:

The correct Location is sent and the related building process is written on the Confluence Page.

1 23 6.0848 (0.0099)  C>SV3.3(480)  application_data

    ---------------------------------------------------------------

    GET /prx/000/http/localhost/ldappasschange?server=win_ad HTTP/1.1

    Host: 192.168.100.176:60443

    Connection: Keep-Alive

    User-Agent: Mozilla/MotionPro 1.x  (Windows)MSIE(compatible; MSIE; Windows NT)

    Content-Type: application/x-www-form-urlencoded

    Cookie: AN_nav1=1%3dopen%262%3dbuttons%263%3dright%264%3dclosed%265%3d623d0451%26eoc;ANsession0000605143676057=ldap-cert+623d0451_a859f5f8c2daea33649f2f2ebe701f73;ANStandalone=true

1 24 6.0899 (0.0050)  S>CV3.3(4480)  application_data

    ---------------------------------------------------------------

    HTTP/1.1 200 OK

    X-Frame-Options: SAMEORIGIN

    Content-Security-Policy: frame-ancestors 'self'; script-src 'self' 'unsafe-inline' 'unsafe-eval'; object-src 'self'

    X-Content-Type-Options: no-sniff

    X-XSS-Protection: 1; mode=block

    Strict-Transport-Security: max-age=31536000; includeSubDomains

    X-Content-Security-Policy: allow self

    X-WebKit-CSP: script-src 'self' 'unsafe-inline' 'unsafe-eval'; object-src 'self'

    Referrer-Policy: strict-origin-when-cross-origin

    X-Permitted-Cross-Domain-Policies: none

    X-Download-Options: noopen

    Content-Length: 3756

    Content-Language: en-us

    Content-Type: text/html; charset=utf-8

    Cache-Control: no-cache

    Connection: Keep-Alive

1 25 13.9698 (7.8799)  C>SV3.3(640)  application_data

    ---------------------------------------------------------------

    POST /prx/000/http/localhost/ldappasschange?server=win_ad HTTP/1.1

    Host: 192.168.100.176:60443

    Content-Length: 63

    Connection: Keep-Alive

    User-Agent: Mozilla/MotionPro 1.x  (Windows)MSIE(compatible; MSIE; Windows NT)

    Content-Type: application/x-www-form-urlencoded

    Cookie: AN_nav1=1%3dopen%262%3dbuttons%263%3dright%264%3dclosed%265%3d623d0451%26eoc;;AN_nav1=1%3dopen%262%3dbuttons%263%3dright%264%3dclosed%265%3d623d0451%26eoc;ANsession0000605143676057=ldap-cert+623d0451_a859f5f8c2daea33649f2f2ebe701f73;ANStandalone=true
new_pass=1qaz@WSX&confirm=1qaz@WSX&option=Change+Password%28%29