batch not works as expected behind nginx in prod

[wenerme]

Local dev works

prod not works, keep retry

I made a check/sse using hono streamSSE, works as expected in prod

this is the nginx conf

    location /xyz/ {
        proxy_pass ${SIDECAR_SERVER_URL}/;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;

        # SSE (Server-Sent Events) support
        proxy_http_version 1.1;
        proxy_set_header Connection '';
        proxy_buffering off;
        proxy_cache off;
        proxy_read_timeout 86400s;
        chunked_transfer_encoding on;

        # CORS headers
        add_header 'Access-Control-Allow-Origin' '*' always;
        add_header 'Access-Control-Allow-Methods' 'GET, POST, PUT, DELETE, OPTIONS' always;
        add_header 'Access-Control-Allow-Headers' 'DNT,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Range,Authorization' always;
        add_header 'Access-Control-Expose-Headers' 'Content-Length,Content-Range' always;

        if ($request_method = 'OPTIONS') {
            add_header 'Access-Control-Allow-Origin' '*';
            add_header 'Access-Control-Allow-Methods' 'GET, POST, PUT, DELETE, OPTIONS';
            add_header 'Access-Control-Allow-Headers' 'DNT,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Range,Authorization';
            add_header 'Access-Control-Max-Age' 1728000;
            add_header 'Content-Type' 'text/plain; charset=utf-8';
            add_header 'Content-Length' 0;
            return 204;
        }
    }

I dont know where to look at

[dosubot[bot]]

Hi @wenerme! I'm Dosu and I’m helping the orpc team.

The batch endpoint likely fails behind nginx due to issues with response headers—especially Content-Length and Content-Encoding. If these headers are set incorrectly (for example, if the body size doesn't match Content-Length), browsers will see an empty or malformed response and keep retrying. This is common when proxying or streaming responses, and nginx can amplify the problem if buffering or chunked transfer settings interact badly with your app.

To fix this, make sure that when you proxy or forward responses, you delete both the content-length and content-encoding headers before returning the response to the client. This avoids decoding mismatches and fetch failures (reference, reference). Also, avoid using plugins that proxy native Response objects together with the batch handler—they are not compatible.

For debugging, log the raw request and response headers and bodies for your batch endpoint in both local and production environments. Compare them, focusing on those headers and the actual body size. This will help you spot where things diverge.

SSE works because its streaming model and headers are simpler and less likely to trigger these issues with nginx. Batch endpoints, especially if they use chunked or streaming responses, are more sensitive to header mismatches and proxy quirks.

To reply, just mention @dosu.

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[unnoq]

Let try different mode: https://orpc.unnoq.com/docs/plugins/batch-requests#batch-mode

[wenerme]

@unnoq
seems caused but using url in batch request

the sevrer is hebind nginx

reverse proxy

/xyz/api/rpc -> /api/rpc

the frontend send request to

http://127.0.0.1/xyz/api/rpc

but the server unable to handle this No procedure matched

how can i handle this ?

[unnoq]

Change the prefix when calling .handle

[wenerme]

but I expeced to work with the original path

this seems resolve the problem

new BatchHandlerPlugin({
	mapRequestItem: (request, { request: req, prefix }) => {
		// Handle URL prefix mismatch when server is behind a reverse proxy
		// e.g., nginx rewrites /xyz/api -> /api, but batch request contains /xyz/api/...
		let url = request.url;
		const a = url.pathname;

		if (prefix && !a.startsWith(prefix)) {
			const idx = a.indexOf(prefix);
			if (idx > 0) {
				url.pathname = a.slice(idx);
			}
		}

		return {
			...request,
			url,
		};
	},
})

[unnoq]

@wenerme you should extends the headers too: https://github.com/unnoq/orpc/blob/ea1d4fd27f6f6b0aee28f1f7d4cc0fcbdd0f8dd0/packages/server/src/plugins/batch.ts#L57-L63