Error fetching proxied request: unexpected end of file

[jonaseicher]

yarn why http-proxy-middleware OR npm ls http-proxy-middleware output (mask private folder names with *****)

% npm ls http-proxy-middleware
***/my-node-proxy
└── [email protected]

• [X] I understand project setup issues should be asked on StackOverflow or in GitHub Discussions.
• [X] I updated to latest http-proxy-middleware.

Describe the bug (be clear and concise)

When receiving a 204 (with no body) proxyResponse, the endpoint using http-proxy-middleware returns a 200 response with body: Error fetching proxied request: unexpected end of file

The error seems to happen in responseInterceptor, maybe in the on('data) handler?:

function responseInterceptor(interceptor) { return async function proxyRes(proxyRes, req, res) { const originalProxyRes = proxyRes; let buffer = Buffer.from('', 'utf8'); // decompress proxy response const _proxyRes = decompress(proxyRes, proxyRes.headers['content-encoding']); // concat data stream _proxyRes.on('data', (chunk) => (buffer = Buffer.concat([buffer, chunk]))); [...] _proxyRes.on('error', (error) => { res.end(Error fetching proxied request: ${error.message}); }); }; }

Step-by-step reproduction instructions

Create an endpoint with a middleware with a responeInterceptor like this:

app.use('/abc/someurl', createProxyMiddleware({
        target: 'sometarget',
        changeOrigin: true,
        pathRewrite: {
            [`^/abc`]: '',
        },
        selfHandleResponse: true,
       onProxyRes: responseInterceptor(async (responseBuffer: Buffer) => {
              return responseBuffer;
           }),
}

and use it to call an endpoint that returns a 204 response (without a body)

Expected behavior (be clear and concise)

endpoint should return the 204 response

What http-proxy-middleware configuration are you using?

see step-by-step reproduction

What OS/version and node/version are you seeing the problem?

macOS 11.5.2 (20G95)
npm -v  
6.14.8
node -v
v14.15.1

Additional context (optional)

No response

[jonaseicher]

Maybe I am using responseInterceptor incorrectly? I have tried returning the responseBuffer and also returning empty string but both show the same behaviour

[jonaseicher]

this is the proxy response being handled:

statusCode: 204
headers:
access-control-allow-headers: authorization,Access-Control-Allow-Origin,Content-Type,SOAPAction 
access-control-allow-methods: GET 
access-control-allow-origin: * 
access-control-expose-headers:  
activityid: asdfsadf-9e0f-4f02-9c08-c2cfe1032291 
cache-control: proxy-revalidate 
connection: keep-alive 
content-type: application/json;charset=utf-8 
date: Tue, 24 Aug 2021 13:16:53 GMT 
custom-reqid: U-320:AFDF8B41-2E53-46C2-809C-599F06784DFC 
strict-transport-security: max-age=15724800; includeSubDomains