Received RpcError is always code 2: Incomplete response

[WindFreaker]

Hi, I am struggling to send error information from my Tonic gRPC server to my gRPC web client. Every time I receive an RpcError on the client, it always comes out as code 2 with the message "Incomplete response".

Here is a snippet of my client code (in case I am doing anything glaringly wrong):

client.beginRegistration(request, {}, async (err, response) => {

	if (err) {
		console.log(`Error: ${err.message}`);
	}

	...

}

However when I inspect the network information for the request, I see headers that contain my error information.

[sampajano]

@WindFreaker Hi thanks for the report.

In your grpc-message response header, it says:

The%20Observer%20is%20currently%20accepting%20new%20registration%20requests%20and%20you%20should%20not%20have%20more%20than%2020%20unexpired.

Which seems to indicate a registration issue? :)

[sampajano]

Ah, I see. Got it.

I assume you're using the grpc-web support in Tonic, right?

wrt RpcError, could you share the code and metadata received as well?

[WindFreaker]

Yes, the backend is built with Tonic and its proxy-free gRPC web support.

Here are all fields on the returned RpcError.

[sampajano]

Ahh i see! Thanks for the info :)

Could you try experiment with with provided echo test and compare how response headers are different from our usual Envoy integration?

I guess this could be an incompatibility with tonic implementation, or just some configuration problems.

[WindFreaker]

It seems that it doesn't use the same headers at all.

Response headers:

HTTP/1.1 200 OK
grpc-accept-encoding: identity
grpc-encoding: identity
content-type: application/grpc-web-text+proto
date: Mon, 07 Apr 2025 23:13:58 GMT
x-envoy-upstream-service-time: 3
access-control-allow-origin: http://localhost:8081
access-control-expose-headers: custom-header-1,grpc-status,grpc-message
server: envoy
transfer-encoding: chunked

Request headers:

POST /grpc.gateway.testing.EchoService/EchoAbort HTTP/1.1
Host: localhost:8080
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:137.0) Gecko/20100101 Firefox/137.0
Accept: application/grpc-web-text
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate, br, zstd
Content-Type: application/grpc-web-text
X-User-Agent: grpc-web-javascript/0.1
X-Grpc-Web: 1
Content-Length: 16
Origin: http://localhost:8081
DNT: 1
Connection: keep-alive
Referer: http://localhost:8081/
Sec-Fetch-Dest: empty
Sec-Fetch-Mode: cors
Sec-Fetch-Site: same-site
Priority: u=0

[WindFreaker]

For comparison here is the headers of my failing request.

Response:

HTTP/1.1 200 OK
content-type: application/grpc-web+proto
grpc-status: 14
grpc-message: The%20server%20is%20not%20currently%20accepting%20new%20registrations%20and/or%20your%20invite%20code%20has%20expired.
content-length: 0
date: Mon, 07 Apr 2025 23:20:40 GMT

Request:

POST /test.AccountService/BeginRegistration HTTP/1.1
Host: [::1]:50051
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:137.0) Gecko/20100101 Firefox/137.0
Accept: */*
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate, br, zstd
Content-Type: application/grpc-web+proto
X-User-Agent: grpc-web-javascript/0.1
X-Grpc-Web: 1
Content-Length: 24
Origin: https://[::1]:4000
DNT: 1
Connection: keep-alive
Sec-Fetch-Dest: empty
Sec-Fetch-Mode: cors
Sec-Fetch-Site: same-site
Priority: u=0

[WindFreaker]

I found someone with the identical issue to me: hyperium/tonic#1968

The fix was indeed adding the header access-control-expose-headers: grpc-status,grpc-message.

[sampajano]

Great! Thank you for sharing the solution! Glad you were able to figure it out! :)