javascript
WebSocket subprotocol negotiation failed
WebSocket.*subprotocol.*not supported|Sec-WebSocket-Protocol.*mismatch
Fixes
- 1.Ensure client requests a subprotocol the server supports: new WebSocket(url, ['graphql-ws'])
- 2.Server must echo back one of the requested subprotocols in the handshake response
- 3.Check for version mismatch: 'graphql-ws' vs 'subscriptions-transport-ws' (deprecated)
websocketsubprotocolnegotiation
Related Errors
javascript3 fixes
Cannot read property of undefined
Cannot read propert(y|ies) of undefined
- •Add optional chaining (?.)
- •Check if object exists before accessing
javascript3 fixes
Cannot read property of null
Cannot read propert(y|ies) of null
- •Add null check before access
- •Use optional chaining (?.)
javascript3 fixes
TypeError: X is not a function
is not a function
- •Check spelling of method name
- •Verify import is correct