MacBook Air: HP printer expired certificate after reset

This issue usually happens when macOS caches the printer’s previous TLS certificate and continues to treat the printer as untrusted after a factory reset. Even if the printer generates a new certificate, the Mac may still be referencing the old one in its printing or keychain trust records. Your goal, then, is to completely remove the cached printer identity and allow macOS to establish a fresh trust relationship with the printer.

I suggest that you start by clearing the printer system configuration on the Mac.

1. Open System Settings → Printers & Scanners, then right-click (or Control-click) in the empty area of the printer list and choose Reset printing system. The result: This removes all printers, queues, and cached printer certificates. Restart the Mac afterward. Once the Mac is back up, add the printer again using AirPrint rather than the HP driver if possible.
2. Next, check whether the expired certificate is still stored in Keychain. Open Keychain Access, search for the printer’s hostname or IP address, and delete any certificate entries related to that printer. If you see entries labeled with the printer’s IP (for example `192.168.x.x`) or HP printer TLS certificates, remove them. After deleting them, restart the Mac again so macOS rebuilds trust records.
3. Next, confirm the printer itself has generated a fresh certificate.

Finally, if the certificate error still appears after these steps, it’s often caused by macOS caching the printer identity via Bonjour. In that case, temporarily change the printer’s hostname in the printer’s network settings (for example from `HP9019e` to `HP9019e-new`), reboot the printer, and add it again. This forces macOS to treat it as a completely new device rather than associating it with the old certificate.