EC
TS5104
TypeScriptERRORNotableConfigHIGH confidence

Option 'X' is redundant and cannot be specified with option 'X'.

Production Risk

Build will fail; resolve before shipping.

What this means

A compiler configuration error (TS5104): Option 'X' is redundant and cannot be specified with option 'X'.. This diagnostic is emitted by the TypeScript compiler when option 'X' is redundant and cannot be specified with option '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 TS5104 during type checking.

trigger — this will error
trigger — this will error
// Triggers TS5104
// Option 'X' is redundant and cannot be specified with option 'X'.

expected output

error TS5104: Option 'X' is redundant and cannot be specified with option '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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