nginx protocol_error ai_generated true

upstream sent invalid HTTP version while reading response header from upstream

ID: nginx/upstream-sent-invalid-http-version

Also available as: JSON · Markdown · 中文

80%Fix Rate

85%Confidence

1Evidence

2024-03-15First Seen

Version Compatibility

Version	Status	Introduced	Deprecated	Notes
nginx-1.24.0	active	—	—	—
nginx-1.25.3	active	—	—	—
nginx-1.26.0	active	—	—	—

Root Cause

The upstream server returns a response with an unrecognized or malformed HTTP version string (e.g., HTTP/1.0, HTTP/2.0, or HTTP/3).

generic

中文

上游服务器返回的响应中包含无法识别或格式错误的 HTTP 版本字符串（例如 HTTP/1.0、HTTP/2.0 或 HTTP/3）。

Official Documentation

https://nginx.org/en/docs/http/ngx_http_proxy_module.html#proxy_pass

Workarounds

90% success Set proxy_http_version to 1.1 or 2.0 in the location block to match the upstream server's expected protocol. Example: location /api/ { proxy_pass http://backend; proxy_http_version 1.1; proxy_set_header Connection ""; }
```
Set proxy_http_version to 1.1 or 2.0 in the location block to match the upstream server's expected protocol. Example:
location /api/ {
    proxy_pass http://backend;
    proxy_http_version 1.1;
    proxy_set_header Connection "";
}
```
85% success If the upstream is a custom or legacy server, ensure it returns a valid HTTP version string (e.g., 'HTTP/1.1 200 OK'). Check the upstream application logs for version misconfiguration.
```
If the upstream is a custom or legacy server, ensure it returns a valid HTTP version string (e.g., 'HTTP/1.1 200 OK'). Check the upstream application logs for version misconfiguration.
```

中文步骤

Set proxy_http_version to 1.1 or 2.0 in the location block to match the upstream server's expected protocol. Example:
location /api/ {
    proxy_pass http://backend;
    proxy_http_version 1.1;
    proxy_set_header Connection "";
}

If the upstream is a custom or legacy server, ensure it returns a valid HTTP version string (e.g., 'HTTP/1.1 200 OK'). Check the upstream application logs for version misconfiguration.

Dead Ends

Common approaches that don't work:

60% fail
Forcing HTTP/1.0 on a modern upstream that uses chunked encoding or keepalive will cause protocol mismatch.
90% fail
The error is about the response version, not the request path.
95% fail
This error is a protocol-level error, not a buffer size issue.