nginx config_error ai_generated true

upstream sent too big header while reading response header from upstream

ID: nginx/upstream-sent-too-big-header-while-reading-response-header

Also available as: JSON · Markdown · 中文
85%Fix Rate
87%Confidence
1Evidence
2023-08-15First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
nginx 1.18.0 active — — —
nginx 1.20.2 active — — —
nginx 1.22.1 active — — —
nginx 1.24.0 active — — —
nginx 1.25.3 active — — —

Root Cause

The upstream server sends HTTP response headers that exceed the proxy_buffer_size or large_client_header_buffers limit, often due to large cookies or custom headers.

generic

中文

上游服务器发送的HTTP响应头超过了proxy_buffer_size或large_client_header_buffers的限制，通常由大型cookie或自定义头引起。

Official Documentation

http://nginx.org/en/docs/http/ngx_http_proxy_module.html#proxy_buffer_size

Workarounds

  1. 85% success Increase proxy_buffer_size to 8k or more in the location block: proxy_buffer_size 8k; proxy_buffers 8 8k; 
    Increase proxy_buffer_size to 8k or more in the location block: proxy_buffer_size 8k; proxy_buffers 8 8k;
  2. 75% success Optimize upstream application to reduce header size, e.g., limit cookie size or remove unnecessary custom headers 
    Optimize upstream application to reduce header size, e.g., limit cookie size or remove unnecessary custom headers
  3. 60% success Set proxy_buffering off as a last resort: proxy_buffering off; (increases memory but bypasses buffer limit) 
    Set proxy_buffering off as a last resort: proxy_buffering off; (increases memory but bypasses buffer limit)

中文步骤

  1. 在location块中将proxy_buffer_size增加到8k或更大：proxy_buffer_size 8k; proxy_buffers 8 8k;
  2. 优化上游应用以减少头部大小，例如限制cookie大小或移除不必要的自定义头部
  3. 作为最后手段关闭proxy_buffering：proxy_buffering off;（增加内存但绕过缓冲区限制）

Dead Ends

Common approaches that don't work:

  1. 70% fail

    proxy_buffer_size must be increased in the server/location context; also proxy_buffers number may need adjustment.

  2. 90% fail

    This controls client headers, not upstream response headers; it's irrelevant.

  3. 95% fail

    The issue is on the upstream server side, not client side; cache clearing doesn't help.