I am facing this issue WSError(type: Starscream.ErrorType.upgradeError, message: "Invalid HTTP upgrade", code: 403) when using subscription with Apollo-iOS client. On android side, it’s working fine and on web as well. do you have any idea what could cause this?
Does this issue help solve your problem? Subscription Failure Error WSError(type: Starscream.ErrorType.upgradeError message: \“Invalid HTTP upgrade\”, code: 400)? · Issue #1250 · apollographql/apollo-ios · GitHub
If you are using an http:// url, you may want to try using ws:// instead so it doesn’t have to do an upgrade in the first place!
hi @AnthonyMDev, I was using ws and wss.
We found the issue with my team. It was actually coming from WAF on the server side. We had to break our sever layers one by one to find this as the error message is not clear and was only triggered on. the iOS client.
thanks anyway 
Solved.