WebSocket Connection Error for some users?

Hello everybody,

my company uses shinyproxy for production and it worked well so far, but now we encountered a problem we have not seen before.

They receive the following 403 Error.


The use the latest browser and the app also works for us, the logfiles show no error. Is this problem caused by shinyproxy, nginx or some browser related issue? I assume it has to do something with their firewall, which blocks the websocket connection, but I know almost nothing about these security related issues. Can anyone help me?

Hi, langma!

Did you find a solution?

I’m facing a similar problem.

Hi everybody,

I have exactly the same problem but did not find any solution.

Did anybody solve this?

Thank you very much for your support…


Hi All

I have solved the websocket issue. This was quite a tough one to diagnose however the solution is quite simple.

Put simply, when network activity is inspected we see a request initiator chain i.e. https://mydomain -> wss://mydomain. Now the expected response code for this should be a status 101 or a protocol switch / internal scheme upgrade and NOT a status code 200. The status code 200 actually comes from the corporate firewall / proxy depending if there is a PAC configuration file or not and how (specifically order) the corporate network sources the files.

Now that we know why the issue occurs, lets speak about the fix. The temporary fix is as simple as disabling proxy settings on your browser (client browser) and a more permanent fix should be implemented by the networking team.

With regards to your specific error, this is a 403 - unauthorized error, this could also be a result of the PAC file depending on if users need to be routed into your network.

Hope this helps.

1 Like

Hi all,

we now have the problem that our client seem to block websocket in general, ie. we see a status 403 WebSocketBlock after starting the app.


Has anybody a solution for this?

Thank you very much

Hello Thomas,

Whats is your problem? The app fail to load or the app grays out after a while?