EC
TS6351
TypeScriptERRORNotableConfigHIGH confidence

Project 'X' is up to date because newest input 'X' is older than output 'X'

Production Risk

Build will fail; resolve before shipping.

What this means

A compiler configuration error (TS6351): Project 'X' is up to date because newest input 'X' is older than output 'X'. This diagnostic is emitted by the TypeScript compiler when project 'X' is up to date because newest input 'X' is older than output 'X'.

Why it happens
  1. 1Incorrect TypeScript syntax or type usage
  2. 2Type mismatch between declared and actual value
How to reproduce

TypeScript compiler reports TS6351 during type checking.

trigger — this will error
trigger — this will error
// Triggers TS6351
// Project 'X' is up to date because newest input 'X' is older than output 'X'

expected output

error TS6351: Project 'X' is up to date because newest input 'X' is older than output 'X'

Fix

Fix the tsconfig.json option

WHEN When a compiler option is invalid or missing

Fix the tsconfig.json option
// tsconfig.json
{
  "compilerOptions": {
    // Review and correct the flagged option
  }
}
// Run: npx tsc --showConfig to see effective config

Why this works

TypeScript validates tsconfig.json options; check the official tsconfig reference for valid values.

Sources
Official documentation ↗

TypeScript Compiler Diagnostics

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