detected a problem with assertion: Unable to establish security of incoming assertion.

[Peter Schober]

George Maynard via users <users at shibboleth.net> [2024-09-26 18:43 CEST]:
> 2024-09-26 10:50:12 WARN Shibboleth.SSO.SAML2 [2] [default]: error processing incoming assertion: Unable to establish security of incoming assertion.

How to find the answer yourself:

SP documentation: https://shibboleth.atlassian.net/wiki/spaces/SP3/overview
  -> Troubleshooting: https://shibboleth.atlassian.net/wiki/spaces/SP3/pages/2065334299/Troubleshooting
  -> Common errors: https://shibboleth.atlassian.net/wiki/spaces/SP3/pages/2065335423/CommonErrors
  -> 3rd entry on that page.

HTH,
-peter