Today users reported trying to login to a Posit Connect server was returning an error message saying "There was a problem logging in. Please try again." It's running on a Linux server using SAML authentication to our campus Shibboleth instance, and has been working for some time. In /var/log/rstudio-connect.log, I'm seeing
2023/09/11 13:38:54 /connect/src/connect/vendor/github.com/rstudio/saml/sp/sp.go:175: (saml) SAML request received with path /login
2023/09/11 13:38:54 /connect/src/connect/vendor/github.com/rstudio/saml/sp/sp.go:175: (saml) Found a SAML encryption key
2023/09/11 13:38:54 /connect/src/connect/vendor/github.com/rstudio/saml/sp/sp.go:175: (saml) Creating authentication request
2023/09/11 13:38:54 /connect/src/connect/vendor/github.com/rstudio/saml/sp/sp.go:175: (saml) Returning authentication request as redirect
2023/09/11 13:38:55 /connect/src/connect/vendor/github.com/rstudio/saml/sp/sp.go:175: (saml) SAML request received with path /login/saml/acs
2023/09/11 13:38:55 /connect/src/connect/vendor/github.com/rstudio/saml/sp/sp.go:175: (saml) Found a SAML encryption key
2023/09/11 13:38:55 /connect/src/connect/vendor/github.com/rstudio/saml/sp/sp.go:175: (saml) Handling authentication response
2023/09/11 13:38:55 SAML handling error trying to read assertion from SAML response: cannot validate signature on Response: Cert is not valid at this time
I've doublechecked that the TLS certificate that nginx itself is using on the server isn't the problem. Any ideas?