# Build error by create-react-app **URL:** \ **Category:** Support\ **Tags:** building\ **Created:** [August 4, 2020, 6:16pm UTC](https://answers.netlify.com/t/build-error-by-create-react-app/20147 "2020-08-04T18:16:41Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![joomation](https://sea1.discourse-cdn.com/netlify/user_avatar/answers.netlify.com/joomation/32/14215_2.png) [@joomation](https://answers.netlify.com/u/joomation)\ **Post date:** [August 4, 2020, 6:16pm UTC](https://answers.netlify.com/t/build-error-by-create-react-app/20147/1 "2020-08-04T18:16:41Z")
I don’t know why the following error occurs when I build using create-react-app . It works fine locally. > **[Netlify App](https://app.netlify.com/sites/eunjoohyung/deploys/5f29a4df5a5e6a00074518f0)** > > Start building the best web experiences in record time ---
**Author:** ![perry](https://sea1.discourse-cdn.com/netlify/user_avatar/answers.netlify.com/perry/32/16_2.png) [@perry](https://answers.netlify.com/u/perry)\ **Post date:** [August 5, 2020, 3:50pm UTC](https://answers.netlify.com/t/build-error-by-create-react-app/20147/2 "2020-08-05T15:50:22Z")
hi there, please see this topic for more information and some fixes: > [@New CI=true build configuration, "Treating warnings as errors because process.env.CI = true"](https://answers.netlify.com/t/new-ci-true-build-configuration-treating-warnings-as-errors-because-process-env-ci-true/14434/): > > Beginning on June 15, 2020 Netlify will start a gradual rollout of adding the environment variable CI to build environments, with the value of true . This environment variable, short for Continuous Integration, is commonly set in various CI environments like Travis CI and Github Actions, among many others. The ecosystem has largely agreed to use this environment setting to detect when a build is executing in a CI environment, as opposed to a local development environment. This setting allows…