> Source: [sk44645](https://support.checkpoint.com/results/sk/sk44645)

# sk44645 - 'Could not validate the certificate used by gateway...' error when trying to authenticate Client-to-Site users on Security Gateway using certificate that was issued by external CA

| Property | Value |
|----------|-------|
| Solution ID | sk44645 |
| Date Created | 2010-04-26 |
| Last Modified | 2017-02-12 |
| Technical Level | Advanced |
| Products | Security Gateway |
| Versions | R82.10, R82, R81.20 |

## Symptoms

- When trying to authenticate Client-to-Site users on Security Gateway using certificate that was issued by external CA, receive the following error:   

`Could not validate the certificate used by gateway [Security Gateway Name] at site [Site Name]. Cannot complete certificate chain CN=[Certificate] IKE negotiation failed Connection failed.`

## Cause

The certificate generated is not issued from a root CA, which has "All issuance policies" option.

## Solution

This solution requires authentication. Please log in to view the full solution.

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