SolvedDefinitelyTyped Subsequent property declarations must have the same type...

Latest changes by @jacobwgillespie @RyanCavanaugh may have caused this issue. "@ types/react": "^16.3.11" causes this error because it loads 16.3.12 which breaks. Removing ^ from the version like "16.3.11" fixes the problem.

The TS starter kit of Microsoft fails too. https://github.com/Microsoft/TypeScript-React-Starter

@allada I was able to reproduce with your pinned versions using yarn (are you using yarn?) - here's what's going on.

This is the package.json:

{
  "dependencies": {
    "@types/react": "16.3.9",
    "@types/react-dom": "16.0.5",
    "react": "16.3.1",
    "react-dom": "16.3.1",
    "typescript": "^2.8.3"
  }
}

So you'll get @types/react at version 16.3.9 and @types/react-dom at version 16.0.5, because you explicitly asked for those. However, @types/react-dom lists a dependency on @types/react as the following:

"@types/react": "*"

Yarn interprets this as "the latest version of @types/react", so it installs an additional version of the package. You can see this in the resulting yarn.lock:

"@types/react-dom@16.0.5":
  version "16.0.5"
  resolved "https://registry.yarnpkg.com/@types/react-dom/-/react-dom-16.0.5.tgz#a757457662e3819409229e8f86795ff37b371f96"
  dependencies:
    "@types/node" "*"
    "@types/react" "*"

"@types/react@*":
  version "16.3.12"
  resolved "https://registry.yarnpkg.com/@types/react/-/react-16.3.12.tgz#68d9146f3e9797e38ffbf22f7ed1dde91a2cfd2e"
  dependencies:
    csstype "^2.2.0"

"@types/react@16.3.9":
  version "16.3.9"
  resolved "https://registry.yarnpkg.com/@types/react/-/react-16.3.9.tgz#15be16b53c89aac558cf6445774502b2792555ff"
  dependencies:
    csstype "^2.2.0"

So you will have versions v16.3.9 and v16.3.12 of the types package simultaneously being used, which causes the error.

There's two ways I know of to fix this:

1. Update to the latest version of the @types/react package in your package.json

2. Add a resolutions section to your package.json to tell Yarn to resolve the dependency differently:

   {
     "resolutions": {
       "@types/react": "16.3.9"
     },
     "dependencies": {
       "@types/react": "16.3.9",
       "@types/react-dom": "16.0.5",
       "react": "16.3.1",
       "react-dom": "16.3.1",
       "typescript": "^2.8.3"
     }
   }

I tried npm v5.6.0 and it does not seem to have the same problem as it interprets a dependency on * as "any".

This is being tracked as an issue with Yarn at yarnpkg/yarn#4489.

as suggested by @jacobwgillespie

Note that most of the time, what's going on is you have a particular dependency like @types/react duplicated in your yarn.lock. For instance if you have a version of the package that is depended on by two other packages, then you upgrade one of those packages, Yarn will oftentimes add a second entry for the shared dep.

The fix for me is usually manually removing the resolutions for @types/react from the yarn.lock file, then re-running yarn so that it's re-locked as a single dependency.

Also as a side note, you may want to check that you don't have multiple versions of @types/react inside your yarn.lock. Yarn can incorrectly resolve the package when upgrading: #24711.

There are some fixes mentioned there in that thread, or you can manually edit your yarn.lock, remove all the instances of @types/react and then re-run yarn install to make it re-resolve.

I deleted yarn.lock, reinstalled the modules and everything working for me now, thanks!

Fixed by adding resolutions to package.json as suggested by @jacobwgillespie

"resolutions": {
  "@types/react": "16.3.18"
},