Start Profiling Generates cURL Error

When the profiler tries to connect to admin-ajax.php, the connection is refused.
Your site is not secure. Here’s the error I receive when connecting to it:

curl: (60) SSL certificate problem: self-signed certificate in certificate chain
More details here: https://curl.se/docs/sslcerts.html
curl failed to verify the legitimacy of the server and therefore could not
establish a secure connection to it. To learn more about this situation and
how to fix it, please visit the web page mentioned above.

Even my browser refuses to access it:

net::ERR_CERT_AUTHORITY_INVALID
its security certificate is not trusted by your computer’s operating system. This may be caused by a misconfiguration or an attacker intercepting your connection.

You need to use a valid SSL certificate and removed the self-signed one.

Our IT department said they have a CA. They are wondering if it might be our firewall if your plugin is trying to access from the outside via https content inspection.

• This reply was modified 3 months, 1 week ago by kennycheung.

Yes it is: the firewall returns a message, but because its SSL certificate is self-signed, it is not displayed. Instead, cURL (or even a browser) stops immediately because of the invalid certificate.
Code Profiler must access the wp-admin/admin-ajax.php endpoint, so make sure your firewall allows your server to connect to itself.
You can go to “Tools > Site Health” to make sure there’s no other error on your WordPress installation too.
Also, check with your admin if they can install a valid certificate for the firewall so that users will know why there are blocked.

Isn’t a certificate issued by Sectigo RSA Domain Validation Secure Server CA a valid certificate?

Site health:

• This reply was modified 3 months ago by kennycheung.

The problem is not the website certificate, but the firewall’s.
Here are its 3 chained certificates:

depth=1 CN = WatchGuard Certificate Authority, O = Parr Lumber
verify error:num=19:self-signed certificate in certificate chain
verify return:1
depth=1 CN = WatchGuard Certificate Authority, O = Parr Lumber
verify return:1
depth=0 CN = 38.142.109.178, O = Parr Lumber
verify return:1

As you can see, the first one is self-signed and that’s the reason why cURL stops processing the request.

IT appears to have fixed the cURL issue. Now I get the error below – even when I use the lowest Accuracy and Precision setting and after IT gave the site more RAM.

The HTTP server returned the following error: 503 Service Unavailable
You can try to select a lower Accuracy and Precision level in the Settings page.

Click on the “Logs” tab, and scroll to the HTTP response log: what do you see?

Only “The HTTP response log is empty.”

Click the “Support” tab, and search for [admin-ajax] . Do you see [access] => OK or an error?

Yes:

[admin-ajax] => Array
    (
        [access] => OK
    )

It seems to work as expected.
Can you check your PHP error log ? It should show the error.
If you can’t find any log, you can enable debugging in WordPress:

1. Edit your wp-config.php file.
2. Search for:
   define('WP_DEBUG', false);
3. Replace with:
   define('WP_DEBUG', true);
4. Add this line below:
   define( 'WP_DEBUG_LOG', true );

Try to run the profiler until you get the error and check the log that will be saved to “/wp-content/debug.log”.

It didn’t add anything to the debug log. I cleared it out the log before running the profiler.

The error occurs at a lower level: either your HTTP server or maybe the firewall?
Can you check their error log?