Duplicate identifier 'LibraryManagedAttributes'

This seems te happen because Yarn resolves multiple versions of a package; @types/react in this particular case. Yarn resolves @types/react from your package.json and as a dependency of @types/react-dom.

Take the following snippet from my package.json:

"devDependencies": {
  "@types/react": "^15.0.16",
  "@types/react-dom": "^0.14.23"
  ...
}

The yarn.lock that is created after you run yarn install contains something similar to this:

"@types/react-dom@^0.14.23":
  version "0.14.23"
  resolved "https://registry.yarnpkg.com/@types/react-dom/-/react-dom-0.14.23.tgz#cecfcfad754b4c2765fe5d29b81b301889ad6c2e"
  dependencies:
    "@types/react" "*"

"@types/react@*":
  version "16.4.14"
  resolved "https://registry.yarnpkg.com/@types/react/-/react-16.4.14.tgz#47c604c8e46ed674bbdf4aabf82b34b9041c6a04"
  dependencies:
    "@types/prop-types" "*"
    csstype "^2.2.0"

"@types/react@^15.0.16":
  version "15.6.19"
  resolved "https://registry.yarnpkg.com/@types/react/-/react-15.6.19.tgz#a5de18afe65b0f29767328836b48c498a5d3a91b"

Notice that @types/react-dom depends on any version of @types/react as indicated by "*". Yarn resolves two versions of @types/react: "16.4.14" and "15.6.19". This results in the type conflicts you mentioned.

The solution is to add a resolutions field to your package.json to tell Yarn to resolve a specific version of @types/react. Take the following sample:

"resolutions": {
  "@types/react": "^15.0.16"
}

Run yarn install again. Notice the change in the yarn.lock file:

"@types/react-dom@^0.14.23":
  version "0.14.23"
  resolved "https://registry.yarnpkg.com/@types/react-dom/-/react-dom-0.14.23.tgz#cecfcfad754b4c2765fe5d29b81b301889ad6c2e"
  dependencies:
    "@types/react" "*"

"@types/react@*", "@types/react@^15.0.16":
  version "15.6.19"
  resolved "https://registry.yarnpkg.com/@types/react/-/react-15.6.19.tgz#a5de18afe65b0f29767328836b48c498a5d3a91b"

Yarn now resolves the same version "15.6.19" for both "@types/react@*" and "@types/react@^15.0.16" dependencies.

I would like to know myself why this is needed. I would expect Yarn to understand it can resolve dependency "@types/react" "*" with "@types/react@^15.0.16" instead of resolving it with the latest version of @types/react.

This seems to be a typescript issue.

My current workaround is adding "skipLibCheck": true to tsconfig.json.

I want to stress that that is only a workaround and not a fix to the problem it self.

I got the same error. I managed to fixed it by removing my '@types/react' and then installing them again.

yarn remove @types/react
yarn add --dev @types/react

For me I had react types duplicated in react-redux, react, and react-intl when I upgraded react-intl. The least intrusive fix that's worked for me so far is to run this:

npx yarn-deduplicate --packages @types/react yarn.lock

If the resulting diff of the lockfile looks correct, go ahead and delete node_modules, then yarn to get fresh packages off the deduplicated lockfile.

In my case the error showed up when the version numbers of @types/react (v17.0.3) and @types/react-dom (v17.0.2) have not been in sync.

To solve the issue, I removed @types/react because it gets hoisted from @types/react-dom. You can verify that by executing yarn why @types/react.

The easiest way to fix this for me was to delete my node_modules directory and yarn.lock/package-lock files and then do a yarn install to reinstall all the node modules.

In our case, we fixed it by

1. Moving all @types/* packages to devDependencies

2. rm -rf yarn.lock and rm -rf node_modules

3. Run yarn install again

Related to the question, running npm list @types/react from the directory of your package.json should list duplicate type definitions found in your project.

Using yarn-deduplicate fixed the issue for me.

Steps:

1. Optional install yarn-deduplicate package or use npx in step two

npm install -g yarn-deduplicate

or

yarn global add yarn-deduplicate

2. Run yarn-deduplicate

yarn-deduplicate yarn.lock --packages @types/react yarn.lock

or

npx yarn-deduplicate --packages @types/react yarn.lock

3. Remove node_modules folder

rm -rf node_modules

4. Reinstall dependencies

yarn install

I have the same issue after yarn upgrade @types/react-router-dom. git diff shows multiple versions of @types/react resolved. In my case, yarn upgrade @types/react resolves the issue. Removing yarn.lock should help.

It seems a fresh (without yarn.lock) install would resolve packages to a consistent state, but a partial upgrade would not resolve the dependencies globally. Thus manual tweaks may be necessary to upgrade all involved packages.

What worked for me was deleting react and @types/react from package.json, then in zsh:

rm -rf node_modules/**/react
npm i react @types/react

C:/Users/japa/source/repos/ReactTestApp/TemplateExample/ClientApp/node_modules/@types/react/index.d.ts
TypeScript error in C:/Users/japa/source/repos/ReactTestApp/TemplateExample/ClientApp/node_modules/@types/react/index.d.ts(2835,14):
Duplicate identifier 'LibraryManagedAttributes'.  TS2300

In my case I needed to solve the problem manually (using principle described in TS2300). The problem arose once I added ReactKendo to my project.

1. Went to ClientApp directory in my project ClientApp\node_modules\@types
2. Backed up the react directory and then deleted it
3. Clean + Build + Run project and no more above error occures
4. I recovered the react folder after the bug disappeared and error seems to be gone forever, so it seems to me like typical magic bug somewhere in the universe :-)

I did not need to change anything else in config files.

In my case, I got the error indicate that 'LibraryManagedAttributes' is declared in 2 different locations. Follow the paths, I realized that an installed module also has a package.json file which also add "@types/react" as dep, and its version is not the same as the one in the root package.json file. I changed these two to the same version and the problem was solved.

I had a conflicting version request for react in another module I used. Fixing that and re-installing with yarn didn't help me either.

Using NPM instead of Yarn however solved it for me.

Hope this helps someone.

For me, it caused by only referenced @types/react-redux. Fixed by npm i --save-dev @types/react, and so the package.json looks like this:

  ...
  "devDependencies": {
    "@types/react": "^16.9.19",
    "@types/react-redux": "^7.1.7"
    ...
  }

I had this issue while working with linked dependencies. My linked package lives in a lerna repo, and it had @types/react as a devDependency. I added @types/react as a peerDependency, switched my workflow to yalc, and was able to continue.