The platform is up, but one dependency path is not.

Use this when Linux access methods fail after an auth-module or MFA rollout that changed PAM sequence or control flags. These issues are easy to misread because the operating system still responds while one control path, runtime dependency, or trust assumption is already out of alignment.

The symptom usually appears downstream from the real change.

• Linux assumptions are often changed indirectly by updates, policy, hardware changes, or cleanup work that looked harmless at the time.
• PAM assumptions are often changed indirectly by updates, policy, hardware changes, or cleanup work that looked harmless at the time.
• MFA assumptions are often changed indirectly by updates, policy, hardware changes, or cleanup work that looked harmless at the time.
• Sudo assumptions are often changed indirectly by updates, policy, hardware changes, or cleanup work that looked harmless at the time.