How To Fix SAML2166 - Can't decrypt string: '&1'

SAP Error Message - Details

• Message type: E = Error

• Message class: SAML2 - SAML2 Nachrichten

• Message number: 166

• Message text: Can't decrypt string: '&1'

Self-Explanatory Message

Since SAP believes that this specific error message is 'self-explanatory,' no more information has been given.The majority of messages in the SAP system have a message text, however this is frequently insufficient to comprehend or resolve the problem.

To make things easier, more detailed information is frequently added to describe the issue, how to fix it, and the necessary steps or configuration modifications.

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Smart SAP Assistant

• What is the cause and solution for SAP error message SAML2166 - Can't decrypt string: '&1' ?

  The SAP error message SAML2166, which states "Can't decrypt string: '&1'", typically occurs in the context of Single Sign-On (SSO) configurations using SAML (Security Assertion Markup Language). This error indicates that the system is unable to decrypt a SAML assertion or a related string, which is often due to issues with the encryption keys or certificates used in the SSO setup.
  Causes:
  
  Incorrect Encryption Keys: The keys used for encrypting the SAML assertions may not match the keys configured in the SAP system.
  Expired or Invalid Certificates: The certificates used for encryption may have expired or may not be valid.
  Configuration Issues: There may be misconfigurations in the SAML setup, such as incorrect endpoints or settings in the Identity Provider (IdP) or Service Provider (SP).
  Missing or Incorrect Trust Relationship: The trust relationship between the IdP and SP may not be properly established.
  Corrupted SAML Assertion: The SAML assertion being sent may be corrupted or malformed.
  
  Solutions:
  
  Verify Encryption Keys: Ensure that the encryption keys used by the IdP to encrypt the SAML assertions match the keys configured in the SAP system. This may involve checking the key pairs and ensuring they are correctly imported.
  Check Certificates: Verify that the certificates used for encryption are valid and have not expired. If they have expired, you will need to renew them and update the configuration accordingly.
  Review SAML Configuration: Double-check the SAML configuration settings in both the IdP and SP. Ensure that all endpoints, entity IDs, and other settings are correctly configured.
  Establish Trust Relationship: Ensure that the trust relationship between the IdP and SP is correctly established. This may involve importing the IdP's certificate into the SAP system.
  Test SAML Assertions: Use tools to test the SAML assertions being sent from the IdP to the SAP system. Ensure that they are well-formed and can be decrypted.
  Check Logs: Review the logs in both the SAP system and the IdP for any additional error messages or warnings that may provide more context about the issue.
  
  Related Information:
  
  SAP Documentation: Refer to the official SAP documentation for SAML and SSO configurations for detailed guidance on setting up and troubleshooting SSO.
  Community Forums: Check SAP Community forums or other technical forums for similar issues and solutions shared by other users.
  Support: If the issue persists, consider reaching out to SAP support for assistance, providing them with detailed logs and configuration settings.
  
  By following these steps, you should be able to identify and resolve the cause of the SAML2166 error in your SAP environment.