400
4xxSEO: negativeRFC 9110
HTTP 400 Bad Request
The server could not understand the request due to malformed syntax.
Indexable by Google
No
Link equity passed
No
SEO Impact
Negative
Category
4XX
SEO Impact
If Googlebot encounters a 400, it will not index the page and will treat it as an error. Search Console will report these under "Coverage" → "Excluded" → "404 and soft-404". Unlike 404, a 400 suggests a malformed URL — ensure your URL structure is clean and your server handles all valid URL patterns.
When to Use 400
When the request is malformed: invalid query parameters, missing required fields in an API request, invalid JSON body.
HTTP Response Example
HTTP/1.1 400 Bad Request
Content-Type: application/json
{"error": "invalid_request"}Test with cURL
$ curl -I "https://example.com/?id=invalid<script>"