Failed: Error during WebSocket handshake: 'Connection' header value must contain 'Upgrade'

Hello all,

I am front end engineer, I want to integrate R-shiny app (running in port number 4848) in to my application (running in 8080 port) running in apache-tomcat server.. when I load index.html in apache server it's showing below error.


    <div class="shiny-app-frame">
        <iframe src=""
            sandbox="allow-same-origin allow-scripts allow-forms" height="500px" width="500px">

Console error:-

WebSocket connection to 'wss://' failed: Error during WebSocket handshake: 'Connection' header value must contain 'Upgrade'
y.websocket @ sockjs-0.3.4.min.js:27
y._try_next_protocol @ sockjs-0.3.4.min.js:27
y._didClose @ sockjs-0.3.4.min.js:27
f._ir.onfinish @ sockjs-0.3.4.min.js:27
f.emit @ sockjs-0.3.4.min.js:27
f.onfinish @ sockjs-0.3.4.min.js:27
f.emit @ sockjs-0.3.4.min.js:27
g.xhr.onreadystatechange @ sockjs-0.3.4.min.js:27

Please help me to fix it or share (url) if available.

What version of httpuv are you using? We recently fixed a related issue:

If you install the latest version of httpuv from CRAN (, it will have the fix.

currently I'm using httpuv_1.3.6.2. I shall update and let you know If issue is still happening.

thank you.