EC
TS6399
TypeScriptERRORNotableConfigHIGH confidence

Project 'X' is out of date because buildinfo file 'X' indicates that some of ...

Production Risk

Build will fail; resolve before shipping.

What this means

A compiler configuration error (TS6399): Project 'X' is out of date because buildinfo file 'X' indicates that some of the changes were not emitted. This diagnostic is emitted by the TypeScript compiler when project 'X' is out of date because buildinfo file 'X' indicates that some of the changes were not emitted.

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

TypeScript compiler reports TS6399 during type checking.

trigger — this will error
trigger — this will error
// Triggers TS6399
// Project 'X' is out of date because buildinfo file 'X' indicates that some of the changes were not emitted

expected output

error TS6399: Project 'X' is out of date because buildinfo file 'X' indicates that some of the changes were not emitted

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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