400 The Plain Http Request Was Sent To Https Port

Understanding HTTPS Errors

HTTPS errors can be caused by several factors. One common issue is when the client's request is not being encrypted for a specific URL. In this case, the client has requested to use the HTTPS port (, for example), but the server has not been configured to listen on that port.

Why Is This Error Occurring?

The error message often includes a cryptic "plain Http request" indication, which can be confusing. However, the primary reason for this error is that the client's request is not being encrypted for a specific URL. When a browser requests to use HTTPS port (), it indicates to the server that the request should be handled with encryption. If the server has not been configured to listen on that port, the request will return an "unencrypted" error.

In this scenario, the browser sends a plain Http request (HTTP/1.0) instead of HTTPS. This is often because Internet Service Providers (ISPs) or Content Delivery Networks (CDNs) are not configured to listen on the required port or may have issues with their configuration.

Resolving the Issue

There are several possible solutions for resolving this error. One approach is to update the server's configuration to listen on the HTTPS port. This can be achieved by updating the VirtualHost section in the Apache or IIS configurations.

Cool Solutions

Another solution is to use a third-party service like Cloudflare, which can help resolve HTTPS errors by redirecting traffic through their servers. This way, the client's request will be encrypted for the required URL.