3463958 - "ERROR: Issuer - Bad Signature" when the SAP Web Dispatcher is connecting to the backend system

Access to the system through the SAP Web Dispatcher does not work.

The SAP Web Dispatcher trace file (dev_webdisp) shows an SSL handshake failure similar to the one below:

(...)
[Thr 12081]    => "Failed to verify peer certificate. Peer not trusted."
[Thr 12081] >> ===== SecuSSL ErrStack: =====
[Thr 12081] Peer not trusted
[Thr 12081] ----- BEGIN VERIFICATION RESULT -----
[Thr 12081]  # --- Messages -----------
[Thr 12081]  ERROR: Signature error. Issuer Cert: [AA:AA:AA:AA] CN=[Intermediary CA]. Cert: [BB:BB:BB:BB] CN=[Subject of SSL server certificate].
[Thr 12081]  ERROR: Signature error. Issuer Cert: [CC:CC:CC:CC] CN=[Root CA]. Cert: [DD:DD:DD:DD] CN=[Intermediary CA].
[Thr 12081]  # --- Summary -----------
[Thr 12081]  #01 Certificate (End Entity): VALID
[Thr 12081]   Subject:                      CN=[Subject of SSL server certificate]
[Thr 12081]   Issuer:                       CN=[Intermediary CA]
[Thr 12081]   Fingerprint (SHA256):         BB:BB:BB:BB:BB:BB:BB:BB:BB:BB:BB:BB:BB:BB:BB:BB:BB:BB:BB:BB:BB:BB:BB:BB:BB:BB:BB:BB:BB:BB:BB:BB
[Thr 12081]   Validity:                     Thu Apr 18 07:52:26 2024 / Fri Apr 18 07:52:26 2025
[Thr 12081]   PKI validation:               FAILED: Validation of dependents - Issuer Certificate (ERROR: Issuer - Bad Signature)
[Thr 12081]  #02 Certificate (Issuer):     VALID
[Thr 12081]   Subject:                      CN=[Intermediary CA]
[Thr 12081]   Issuer:                       CN=[Root CA]
[Thr 12081]   Fingerprint (SHA256):         AA:AA:AA:AA:AA:AA:AA:AA:AA:AA:AA:AA:AA:AA:AA:AA:AA:AA:AA:AA:AA:AA:AA:AA:AA:AA:AA:AA:AA:AA:AA:AA
[Thr 12081]   Validity:                     Tue Feb  2 14:06:22 2016 / Sun May 12 12:49:48 2041
[Thr 12081]   PKI validation:               Succeeded
[Thr 12081]  #03 Certificate (Issuer):     VALID
(...)

• SAP Web Dispatcher
• ABAP Platform based system
• SAP NetWeaver based system

KBA , BC-CST-WDP , Web Dispatcher , BC-CST , Client/Server Technology , BC-SEC-SSL , Secure Sockets Layer Protocol , Problem