debugging-websocket-issues

RSV1 errors occur when multiple WebSocketServer instances handle the same upgrade event, causing conflicting compression settings. Diagnose by checking for duplicate upgrade listeners and verify perMessageDeflate configuration matches across all handlers. Fix by routing upgrades through a single noServer instance or ensuring only one upgrade listener processes each connection.

Code 1006 abnormal closures and raw HTTP data on upgraded sockets typically signal conflicting WebSocketServer upgrade handlers writing to the same socket. Verify you have exactly one upgrade event listener per server and that raw frames aren't being corrupted by competing handlers. Consolidate upgrade logic into a single handler.

This error indicates the compression bit (RSV1) is set when perMessageDeflate is disabled or mismatched between client and server. Check your ws WebSocketServer configuration for conflicting compression settings across multiple instances. Ensure perMessageDeflate is consistently enabled or disabled on all upgrade paths.

Capture raw frames and trace upgrade listener execution paths to identify which handler processes each connection. Log WebSocketServer instance creation and upgrade event firing to spot duplicate handlers. Verify socket state before and after frame operations to isolate where corruption occurs.

Multiple instances can coexist only if they handle disjoint upgrade paths or use noServer mode with exclusive routing. Overlapping upgrade listeners cause frame errors and 1006 closures. Use a single noServer instance and route upgrades explicitly, or ensure each instance listens on separate paths with clear ownership.

Use a single noServer WebSocketServer and handle all upgrades through one listener with explicit path or protocol routing. Avoid creating multiple WebSocketServer instances that might claim the same upgrade event. This architecture prevents RSV1 conflicts and ensures consistent compression and frame handling.