Vue Debug Guides

Vue 3 debugging and error handling for runtime issues, warnings, async failures, and hydration bugs. For development best practices and common gotchas, use vue-best-practices.

Reactivity

• Tracing unexpected re-renders and state updates → See reactivity-debugging-hooks
• Ref values not updating due to missing .value access → See ref-value-access
• State stops updating after destructuring reactive objects → See reactive-destructuring
• Refs inside arrays, Maps, or Sets not unwrapping → See refs-in-collections-need-value
• Nested refs rendering as [object Object] in templates → See template-ref-unwrapping-top-level
• Reactive proxy identity comparisons always return false → See reactivity-proxy-identity-hazard
• Third-party instances breaking when proxied → See reactivity-markraw-for-non-reactive
• Watchers only firing once per tick unexpectedly → See reactivity-same-tick-batching

Computed

• Computed getter triggers mutations or requests unexpectedly → See computed-no-side-effects
• Mutating computed values causes changes to disappear → See computed-return-value-readonly
• Computed value never updates after conditional logic → See computed-conditional-dependencies
• Sorting or reversing arrays breaks original state → See computed-array-mutation
• Passing parameters to computed properties fails → See computed-no-parameters

Watchers

• Async operations overwriting with stale data → See watch-async-cleanup
• Creating watchers inside async callbacks → See watch-async-creation-memory-leak
• Watcher never triggers for reactive object properties → See watch-reactive-property-getter
• Async watchEffect misses dependencies after await → See watcheffect-async-dependency-tracking
• DOM reads are stale inside watcher callbacks → See watch-flush-timing
• Deep watchers report identical old/new values → See watch-deep-same-object-reference
• watchEffect runs before template refs update → See watcheffect-flush-post-for-refs

Components

• Child component throws "component not found" error → See local-components-not-in-descendants
• Click listener doesn't fire on custom component → See click-events-on-components
• Parent can't access child ref data in script setup → See component-ref-requires-defineexpose
• HTML template parsing breaks Vue component syntax → See in-dom-template-parsing-caveats
• Wrong component renders due to naming collisions → See component-naming-conflicts
• Parent styles don't apply to multi-root component → See multi-root-component-class-attrs

Props & Emits

• Variables referenced in defineProps cause errors → See prop-defineprops-scope-limitation
• Component emits undeclared event causing warnings → See declare-emits-for-documentation