TS2571: Object is of type 'unknown' TypeScript Origin: On your device OSI layer 7 · Application Last updated 5 Nov 2026

TypeScript: error TS2571: Object is of type 'unknown'.

You used a value typed unknown (often catch (e) or JSON.parse result) without narrowing.

Exact message you may see error TS2571: Object is of type 'unknown'.Object is of type 'unknown'. ts(2571)TS2571 Object is of type 'unknown'error TS2571
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Seen on: TypeScript

Meaning

unknown forces checks before use: if (e instanceof Error) e.message, typeof x === "string", type guards, or validate with zod. In catch clauses with useUnknownInCatchVariables (strict) e is unknown. Avoid casting to any blindly.

Common causes

  • catch (e) accessing e.message
  • JSON.parse / response.json() result unknown
  • Generic unknown params
  • Third-party callbacks typed unknown
  • strict mode enabled recently

⚡ Quick fix

  1. if (e instanceof Error) { console.error(e.message); }
  2. Use type guards/zod to validate
  3. const data = (await res.json()) as MyType only after validation

Detailed fix by platform

TypeScript

  1. try { run(); } catch (e) { const msg = e instanceof Error ? e.message : String(e); }

How to diagnose

  1. Value — unknown?
  2. Guard — typeof/instanceof?
  3. Validation — zod?

🔧 Still not fixed?

Many errors look alike. If the steps above didn’t solve it, one of these is probably what you’re facing:

Where this error sits

Origin: On your device. Errors that are often confused with or caused by this one (click to open):

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