Community

Hello,

I am experiencing an issue connecting WinCC OA 3.21.5.1 to a Siemens PLC OPC UA server.

The connection works with Anonymous authentication, but fails when using Username/Password authentication with the following error:

`BadIdentityTokenRejected`

The WinCC OA log also shows:

`new user password mechanism fails, fallback used`

and:

`Password encryption using DES is deprecated`

The connection works correctly with UA Expert using the same credentials, certificates and security settings:

- Security policy: Basic256Sha256
- Message mode: Sign & Encrypt
- Authentication: Username/Password

I have already re-entered the password and tested a separate connection, but the issue remains.

Could this be a known issue in WinCC OA 3.21.5.1 related to OPC UA password encryption or Username IdentityToken handling? Is there a known fix or hotfix?

Thank you for your help.