What Does This Error Mean: Hpe_Invalid_Constant?

The HPE_INVALID_CONSTANT means Http Parse Error and the invalid constant means that the response is malformed. So the parser can't parse it!

I encountered this issue because I was trying to compress files that were too small. In my specific case, I was creating a readstream of a file that was 83 bytes, and then piping it into a gzip, before finally piping it into the response

fs.createReadStream(file_path).pipe(gzip.createGzip()).pipe(res);

On the requester side, I was then trying to unzip the file

stream = request({"url": "", "timeout": 200000});

//This is where the error was getting thrown
stream.pipe(gzip.createGunzip())

It seems that trying to compress and then decompress a file with a size somewhere less than 200 bytes will totally break this, so that was a gotcha I encountered. I guess the moral of my story is don't compress files that are super tiny!

I've had the same issue when used not decoded params in request URL.

Example:

1. Request to with whitespaces will cause an error

     Error: Parse Error
     at TLSSocket.socketOnData (_http_client.js:440:20)
     at emitOne (events.js:116:13)
     at TLSSocket.emit (events.js:211:7)
     at addChunk (_stream_readable.js:263:12)
     at readableAddChunk (_stream_readable.js:250:11)
     at TLSSocket.Readable.push (_stream_readable.js:208:10)
     at TLSWrap.onread (net.js:597:20)
   bytesParsed: 0,
   code: 'HPE_INVALID_CONSTANT',
   

2. Request to will work fine