LWCIntermediateerror-handlinguxtoast
Implement error handling and user feedback patterns in LWC
Real World Scenario
Users report silent failures when Apex throws validation errors—UI shows infinite spinner.
Expected Answer
• Always set loading=false in finally blocks for imperative calls
• Parse Apex AuraHandledException body for field-level messages
• ShowToastEvent with mode sticky for errors requiring attention
• Inline field errors using lightning-input reportValidity pattern
• Wire errors display friendly fallback not raw error body
• Log correlation Id from server for support without exposing internals
• Disable submit buttons during in-flight requests preventing double submit
Follow-Up Questions & Answers
Click to expand — each follow-up includes a direct, interview-ready answer
Never fail silently. Always set loading=false in finally blocks for imperative calls. Implement retry with exponential backoff and a dead-letter queue for permanent failures. Spinner without terminal state is UX bug—architects require error path review in every LWC PR. Balance speed of delivery with maintainability.
Architect Perspective
Spinner without terminal state is UX bug—architects require error path review in every LWC PR.