---
title: "ERR_CERT_DATE_INVALID on iPhone: cause and fix"
description: "iOS trusts the certificate against the device clock. A phone whose date drifted, or one restored from an old backup, reads a perfectly valid certificate as…"
canonical: "https://lemwatch.com/errors/err-cert-date-invalid/on-iphone"
source: "https://lemwatch.com"
---

# ERR_CERT_DATE_INVALID on iPhone

> iOS trusts the certificate against the device clock. A phone whose date drifted, or one restored from an old backup, reads a perfectly valid certificate as expired or not yet valid.

## Why it happens on iPhone

 iOS trusts the certificate against the device clock. A phone whose date drifted, or one restored from an old backup, reads a perfectly valid certificate as expired or not yet valid.

## The fix on iPhone

 Settings → General → Date & Time → Set Automatically, then reload. If the date was already correct, the certificate really has expired and only the site owner can renew it.

## If that didn't fix it

 iPhone has its own failure mode, but ERR_CERT_DATE_INVALID has a wider set of causes. The most common one overall is: The certificate expired and auto-renewal silently stopped.

 Renew immediately. For Let's Encrypt, run the renewal manually and read the output — the usual cause is a failing HTTP-01 challenge after a redirect or firewall change.

## Check your own domain

 The SSL checker returns the exact notAfter date and days remaining for the hostname, which immediately separates 'genuinely expired' from 'your clock is wrong'.

## Frequently asked questions

### Why does ERR_CERT_DATE_INVALID happen on iPhone?

 iOS trusts the certificate against the device clock. A phone whose date drifted, or one restored from an old backup, reads a perfectly valid certificate as expired or not yet valid.

### How do I fix ERR_CERT_DATE_INVALID on iPhone?

 Settings → General → Date & Time → Set Automatically, then reload. If the date was already correct, the certificate really has expired and only the site owner can renew it.

### What does ERR_CERT_DATE_INVALID mean?

 The certificate the server presented is outside its validity window — almost always expired. Either the certificate genuinely lapsed, or the device's clock is wrong so a valid certificate looks expired.


## Related

- [All causes of ERR_CERT_DATE_INVALID](https://lemwatch.com/errors/err-cert-date-invalid)
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