nginx/nginx · error

400 No required SSL certificate was sent

Error message

400 No required SSL certificate was sent

What it means

Error "400 No required SSL certificate was sent" thrown in nginx/nginx.

Source

Thrown at src/http/ngx_http_special_response.c:272

"<head><title>400 Request Header Or Cookie Too Large</title></head>"
CRLF
"<body>" CRLF
"<center><h1>400 Bad Request</h1></center>" CRLF
"<center>Request Header Or Cookie Too Large</center>" CRLF
;


static char ngx_http_error_495_page[] =
"<html>" CRLF
"<head><title>400 The SSL certificate error</title></head>"
CRLF
"<body>" CRLF
"<center><h1>400 Bad Request</h1></center>" CRLF
"<center>The SSL certificate error</center>" CRLF
;


static char ngx_http_error_496_page[] =
"<html>" CRLF
"<head><title>400 No required SSL certificate was sent</title></head>"
CRLF
"<body>" CRLF
"<center><h1>400 Bad Request</h1></center>" CRLF
"<center>No required SSL certificate was sent</center>" CRLF
;


static char ngx_http_error_497_page[] =
"<html>" CRLF
"<head><title>400 The plain HTTP request was sent to HTTPS port</title></head>"
CRLF
"<body>" CRLF
"<center><h1>400 Bad Request</h1></center>" CRLF
"<center>The plain HTTP request was sent to HTTPS port</center>" CRLF
;

View on GitHub (pinned to 3f6f7824d4)

When it happens

Trigger: Thrown at src/http/ngx_http_special_response.c:272 when the library encounters an invalid state.

Common situations: See trigger scenarios.

Understand the failure class

AI-assisted analysis of nginx/nginx@3f6f7824d4 (2026-08-22). Data as JSON: /api/errors/2b0937c3d7e04cf2. Report an issue: GitHub.