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When running WordPress on localhost using WampServer with HTTPS, you may encounter the following error:
cURL error 60: SSL certificate problem: self-signed certificate
This error often appears when WordPress, Classic Oxygen Builder, WooCommerce, or REST API requests attempt to load external HTTPS resources.
This guide explains what causes the error, why it happens on Wampserver, and quick ways to fix it, following PHP and WordPress best practices.
What Causes cURL Error 60?
WordPress uses PHP cURL to communicate with external servers via HTTPS. PHP cURL performs SSL certificate verification by default.
When using self-signed certificates on localhost, the certificate:
- Is not issued by a trusted Certificate Authority (CA)
- Is not present in PHP’s trusted certificate store
As a result, PHP blocks the HTTPS request and throws:
cURL error 60: SSL certificate problem: self-signed certificateOfficial PHP Explanation: https://www.php.net/manual/en/curl.configuration.php
Official cURL Error Reference: https://curl.se/libcurl/c/libcurl-errors.html
Why This Error Commonly Happens on Wampserver
Wampserver does not ship with:
- A trusted CA certificate bundle
- Automatic local HTTPS trust management
When HTTPS is enabled using a self-signed certificate, PHP cannot verify it, causing WordPress API requests to fail.
This directly affects:
- Classic Oxygen Builder (design sets, templates, editor UI)
- WordPress REST API
- Plugin updates
- Theme updates
- External API calls
Quick Fix (Development Only): Disable SSL Verification in PHP cURL
WordPress Filter Override (Fast debugging only)
If you need an immediate workaround, you can disable SSL verification inside WordPress.
Only use this on localhost – never on production.
Add into functions.php:
add_filter('https_ssl_verify', '__return_false');
This forces WordPress to skip SSL verification.
Source:
https://developer.wordpress.org/reference/hooks/https_ssl_verify/
Note: Security risk – do not use on production.
Wrap up
There are actually three methods to fix this issue: installing a CA Bundle, using a mkcert Trusted SSL installation, or performing a WP SSL Bypass (which is covered in this post). Since I am working on a localhost environment, I chose the WP SSL Bypass method. I hope this post helps you. If it did, please consider buying me a coffee to encourage me to publish more time-saving content.
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