TypeScript: Two different types with this name exist, but they are unrelated

Quick fix

Read the commands before running them. Anything that restarts a service, deletes data or changes permissions should be tried on a non-production system first.

# Find the duplicates, path and version
npm ls @types/react @types/node
# pnpm why @types/react     yarn why @types/react

# Pin one copy for the whole tree (npm 8.3+)
# package.json
"overrides": { "@types/react": "18.3.12" }
# yarn: "resolutions", pnpm: "pnpm.overrides"

# Then flatten and rebuild
rm -rf node_modules package-lock.json && npm install
npx tsc --noEmit

# Confirm only one copy remains
find node_modules -path '*@types/react/package.json' -not -path '*/node_modules/*/node_modules/*'

How to diagnose TypeScript errors

TypeScript errors are the compiler describing a mismatch between what you declared and what you did. Nearly all of them fall into assignability (this shape is not that shape), missing declarations (a JavaScript package with no types), or strict null checks (a value can be undefined on a path you did not handle). Casting with as or any silences the message without fixing the underlying mismatch, which usually reappears at runtime.

If the quick fix above does not resolve it, work through these steps. They apply to this whole class of error, not just to this one message, which is usually what saves the time.

1. Read the error from the innermost "Types of property X are incompatible" line outward. That nested line names the actual mismatch.
2. For missing declarations, try npm i -D @types/<pkg> first; if none exists, write a minimal .d.ts rather than reaching for any.
3. Narrow rather than assert. A type guard, an in check, or an early return preserves safety where as discards it.
4. Use tsc --noEmit --pretty to check the whole project; editors sometimes use a different TypeScript version than the build.
5. Check strict, skipLibCheck and moduleResolution in tsconfig when errors appear only in CI or only in the editor.

Tools worth reaching for

• tsc --noEmit
• ts-node / tsx
• @types/* packages
• typescript-eslint
• editor TS version selector

Authoritative references

Primary documentation for this error, worth reading before applying any fix in production.

📖 docs.npmjs.com

Related TypeScript errors

• TypeScript: 'error' is of type 'unknown' (TS18046)Since TypeScript 4.4, useUnknownInCatchVariables (part of strict) types the catch binding as…
• TypeScript: Argument of type X is not assignable to parameter of type YA function argument's type doesn't match the parameter's declared type. Common when passing…
• TypeScript: Cannot find module './x.js' or its corresponding type declarationsWith module set to node16 or nodenext, TypeScript resolves imports exactly as Node does at…
• TypeScript: Cannot find name 'process'The Node global types are not loaded. Either @types/node is missing, or the…
• TypeScript: Cannot redeclare block-scoped variable 'name'A file with no import or export is treated as a script, not a module, so its top level…
• TypeScript: Cannot use JSX unless the '--jsx' flag is providedA .tsx file was compiled with JSX support off. Either the option is missing, or the editor is…
• TypeScript: Could not find a declaration file for moduleA JS library has no TypeScript type declarations. The library has no built-in types and no…
• TypeScript: Module can only be default-imported using the 'esModuleInterop' flagThe package is CommonJS and sets module.exports directly, so it has no ES default export to…

See all 19 TypeScript errors →

Browse other categories

• HTTP 494xx client errors, 5xx server errors, redirects, headers and protocol problems.
• JavaScript 42npm resolution, async pitfalls, hydration, memory limits and runtime type…
• Database 41Connections, deadlocks, constraints, replication and memory limits.
• AI 35Rate limits, context windows, GPU memory and model-serving failures.
• Network 35Refused connections, timeouts, resets, MTU problems and port exhaustion.
• Python 35Imports, virtual environments, encoding, concurrency and dependency conflicts.
• Kubernetes 34CrashLoopBackOff, ImagePullBackOff, OOMKilled, RBAC, scheduling and storage.
• Docker 27Daemon connectivity, disk space, image pulls, ports and architecture mismatches.
• System 26Disk space, systemd units, file descriptors, OOM killer and scheduled jobs.
• Cloud 25IAM permissions, quotas, service limits and credential failures.
• Security 25JWT validation, CSRF, OAuth grants, SELinux, SSH host keys and CSP.
• TLS 24Untrusted authorities, expiry, hostname mismatch, chains and cipher negotiation.

Something missing or wrong?

This entry is maintained by hand. If the fix is out of date, incomplete, or you have a better one, email a correction and it will be reviewed.