上游发送的标头过大，同时从上游读取响应标头，客户端：10.0.0.1，服务器：example.com，上游：“http://127.0.0.1:8080”
upstream sent too big header while reading response header from upstream, client: 10.0.0.1, server: example.com, upstream: "http://127.0.0.1:8080"
ID: nginx/proxy-buffer-size-too-small
版本兼容性
| 版本 | 状态 | 引入 | 弃用 | 备注 |
|---|---|---|---|---|
| nginx/1.18.0 | active | — | — | — |
| nginx/1.20.0 | active | — | — | — |
| nginx/1.24.0 | active | — | — | — |
| nginx/1.26.0 | active | — | — | — |
根因分析
上游服务器的响应标头超过默认的 proxy_buffer_size（4KB），导致 nginx 拒绝响应并返回 502 错误。
English
The upstream server's response headers exceed the default proxy_buffer_size (4KB), causing nginx to reject the response with a 502 error.
官方文档
https://nginx.org/en/docs/http/ngx_http_proxy_module.html#proxy_buffer_size解决方案
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在 location 或 server 块中将 proxy_buffer_size 增加到 8K 或更大（例如 16K）：`proxy_buffer_size 16k;`
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同时增加 proxy_buffers 以保持一致：`proxy_buffers 8 16k;`
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如果大标头是由于过多 cookie 引起的，请考虑在应用程序级别使用自定义标头压缩或减少 cookie 大小作为长期修复。
无效尝试
常见但无效的做法:
-
70% 失败
proxy_buffers controls the number and size of buffers for the response body, not the initial header buffer.
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60% 失败
proxy_buffering off affects body buffering, not header buffering; the header buffer size is always limited by proxy_buffer_size.
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40% 失败
While this can fix the symptom, it requires application changes that may break features like session management or authentication.