A new browser version has been deployed to all users at a company. After the deployment, users report that they can no longer access the company's secure time-card system, which is hosted by a SaaS…

If an SSL certificate had expired on the SaaS load balancers, both the new and old browser versions would typically display a certificate error, not just the new one.

Federation issues usually relate to authentication and single sign-on problems, which would typically manifest during the login process rather than immediately upon opening the secure site with a security error related to the connection itself.

Modern web browsers frequently deprecate support for older, less secure cryptographic protocols (like older TLS versions) or weak cipher suites. If the SaaS provider's servers are still configured to use these obsolete security technologies, the updated browser would refuse to establish a secure connection, resulting in a security error, while the older browser, which still supports them, would connect successfully.

The question states it's a 'secure time-card system' and a 'security error' is received, indicating a problem with the secure communication handshake, not that the communications were unencrypted; the browser expects encryption but cannot establish it due to protocol incompatibility.