Quick-Fix Summary
- Check the printer's internal date and time — my uncommon tip, and the fix that resolves this more often than replacing anything.
- Try accessing the printer's web page directly, acknowledging the security warning.
- Power cycle the printer as a genuine reset.
- Verify the printer's IP address hasn't unexpectedly changed.
- Reissue or reinstall the certificate if the clock genuinely isn't the cause.
Fix 1: Check the Printer's Internal Date and Time (My Uncommon Tip)
Here's the fix that resolves a meaningful share of "certificate expired" errors, and it's something almost nobody thinks to check because the error message itself points so directly at the certificate rather than anything else.
Digital certificates are validated against a specific date range — a "not valid before" and "not valid after" date — and that validation is checked against whatever date and time the printer itself currently believes it is. If your printer's internal clock has drifted, reset itself (sometimes following a power outage, a firmware update, or simply a battery backup component reaching end of life), or was affected by a daylight saving time transition incorrectly, the printer can conclude a completely valid, unexpired certificate has "expired".
To check and fix this: access the printer's Embedded Web Server if you're able to, and look under Network or General settings for Date and Time. Compare the currently displayed date and time against what it should actually be right now. If it's wrong — even by a surprising amount — correct it manually, or better yet, enable automatic time synchronization via NTP (Network Time Protocol).
Fix 2: Access the Printer's Web Page Despite the Warning
Type the printer's IP address directly into a browser. If you see a security warning about the certificate, look for an option like Advanced or Show Details, and choose to proceed anyway.
Why this works: browsers warn about certificate issues by design, but for a printer on your own trusted local network, this warning doesn't mean the connection itself is compromised — it typically just means the certificate has an issue, which might be exactly the date problem in Fix 1.
Fix 3: Power Cycle the Printer
Turn the printer off, unplug it from the wall for about 30 seconds, then reconnect and power back on. In some cases, a printer's clock can desync due to a temporary internal glitch that a genuine power cycle clears.
Fix 4: Verify the Printer's IP Address Hasn't Changed
Check the printer's currently displayed IP address against what you expect it to be. A printer's IP address can occasionally shift unexpectedly, and if you're trying to reach the printer using an outdated or incorrect address, you might encounter what looks like a certificate error but is actually a connection reaching the wrong destination entirely.
Fix 5: Reissue or Reinstall the Certificate
If you've confirmed the printer's date and time are genuinely correct, and the certificate is still showing as invalid or expired, the certificate itself may actually need to be reissued or reinstalled — through your organization's certificate authority if this is a business network, or through the printer's own self-signed certificate regeneration option.
