HTTP 400 Bad Request vs 526 Invalid SSL Certificate
HTTP 400 (Bad Request) is a 4xx Client Error response, while 526 (Invalid SSL Certificate) is a 5xx Server Error response. 400 indicates that the server cannot process the request due to malformed syntax, invalid request message framing, or deceptive request routing. In contrast, 526 means that cloudflare-specific. The origin's SSL certificate could not be validated.
Description
The server cannot process the request due to malformed syntax, invalid request message framing, or deceptive request routing.
When You See It
When sending malformed JSON, missing required fields, or invalid query parameters.
How to Fix
Check the request body format, validate all required fields, and ensure proper encoding.
Description
Cloudflare-specific. The origin's SSL certificate could not be validated.
When You See It
When using Cloudflare Full (Strict) mode with an invalid origin certificate.
How to Fix
Install a valid SSL certificate on the origin, or use Cloudflare Origin CA certificate.
Key Differences
400 is a 4xx Client Error response, while 526 is a 5xx Server Error response.
HTTP 400: The server cannot process the request due to malformed syntax, invalid request message framing, or deceptive request routing.
HTTP 526: Cloudflare-specific. The origin's SSL certificate could not be validated.
You encounter 400 when when sending malformed JSON, missing required fields, or invalid query parameters.
You encounter 526 when when using Cloudflare Full (Strict) mode with an invalid origin certificate.
When to Use Which
For 400 (Bad Request): Check the request body format, validate all required fields, and ensure proper encoding. For 526 (Invalid SSL Certificate): Install a valid SSL certificate on the origin, or use Cloudflare Origin CA certificate.