Best Fixes
Verify the system clock first, then inspect the certificate dates and trust chain.
If it is your service, renew and deploy the correct certificate chain cleanly.
Error Fix
How to Fix 'certificate has expired'
What this SSL/TLS error actually means and how to determine whether the cert or trust chain is the problem.
This often means the remote certificate really expired, but sometimes the local system clock or trust store is also involved. The right fix depends on which side is actually wrong.
Avoid This
Do not bypass TLS verification as the permanent solution.
Do not assume the remote cert is wrong before checking whether the local machine time is skewed.
Save commands, add notes, and build a Cheatbook with the fixes you want to keep handy.