Understanding "certificate has expired or is not yet valid" errors

[aadityadhruv]

Hi guys,
I've got a small K3S home cluster, and recently I saw these errors in my journal:

Mar 08 13:47:16 hostname k3s[902272]: E0308 13:47:16.941377  902272 authentication.go:73] "Unable to authenticate the request" err="[x509: certificate has expired or is not yet valid: current time 2025-03-08T13:47:16-06:00 is after 2025-03-03T19:40:53Z, verifying certificate SN=7745007516487360706, SKID=, AKID=43:E1:00:3D:53:CB:8D:B5:6D:36:0F:DD:20:25:4C:4B:BB:11:DE:D4 failed: x509: certificate has expired or is not yet valid: current time 2025-03-08T13:47:16-06:00 is after 2025-03-03T19:40:53Z]"

I'm trying to understand what this means. Initially I thought it was my workstation having an invalid config file, but after updating that, my workstation can access the cluster, but this error persists.

What does it mean? Especially what is "SKID" and "AKID"? Are these requests coming from a specific node or host?