Posted in React Native Issues

Cannot create a string longer than 0x3fffffe7 characters in jest-haste-map

   March 25, 2020  1 Comment on Cannot create a string longer than 0x3fffffe7 characters in jest-haste-map

Description:

Getting the following error when starting my app using npx react-native start or npx react-native run-android

I already tried clearing my caches using npx react-native start --reset-cache and cache cleaner scripts from npm

warning: the transform cache was reset.
Loading dependency graph...Failed to construct transformer:  Error: Cannot create a string longer than 0x3fffffe7 characters
    at Object.slice (buffer.js:593:37)
    at Buffer.toString (buffer.js:790:14)
    at Object.readFileSync (fs.js:403:41)
    at getContent (D:\MyApp\node_modules\metro\node_modules\jest-haste-map\build\worker.js:149:41)
    at Object.<anonymous> (D:\MyApp\node_modules\metro\node_modules\jest-haste-map\build\worker.js:199:9)
    at Generator.next (<anonymous>)
    at asyncGeneratorStep (D:\MyApp\node_modules\metro\node_modules\jest-haste-map\build\worker.js:78:24)
    at _next (D:\MyApp\node_modules\metro\node_modules\jest-haste-map\build\worker.js:98:9)
    at D:\MyApp\node_modules\metro\node_modules\jest-haste-map\build\worker.js:103:7
    at new Promise (<anonymous>) {
  type: 'Error',
  code: 'ERR_STRING_TOO_LONG'
}
(node:1972) UnhandledPromiseRejectionWarning: Error: Cannot create a string longer than 0x3fffffe7 characters
    at Object.slice (buffer.js:593:37)
    at Buffer.toString (buffer.js:790:14)
    at Object.readFileSync (fs.js:403:41)
    at getContent (D:\MyApp\node_modules\metro\node_modules\jest-haste-map\build\worker.js:149:41)
    at Object.<anonymous> (D:\MyApp\node_modules\metro\node_modules\jest-haste-map\build\worker.js:199:9)
    at Generator.next (<anonymous>)
    at asyncGeneratorStep (D:\MyApp\node_modules\metro\node_modules\jest-haste-map\build\worker.js:78:24)
    at _next (D:\MyApp\node_modules\metro\node_modules\jest-haste-map\build\worker.js:98:9)
    at D:\MyApp\node_modules\metro\node_modules\jest-haste-map\build\worker.js:103:7
    at new Promise (<anonymous>)
(node:1972) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 1)
(node:1972) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

React Native version:

Run `react-native info` in your terminal and copy the results here.

System:
    OS: Windows 10 10.0.18363
    CPU: (8) x64 Intel(R) Core(TM) i7-4770K CPU @ 3.50GHz
    Memory: 2.34 GB / 15.91 GB
  Binaries:
    Node: 12.16.1 - C:\Program Files\nodejs\node.EXE
    Yarn: 1.13.0 - ~\AppData\Roaming\npm\yarn.CMD
    npm: 6.11.3 - ~\AppData\Roaming\npm\npm.CMD
  SDKs:
    Android SDK:
      API Levels: 24, 25, 26, 28
      Build Tools: 23.0.1, 23.0.3, 25.0.2, 26.0.1, 26.0.2, 28.0.3
  IDEs:
    Android Studio: Version  3.5.0.0 AI-191.8026.42.35.6010548
  npmPackages:
    react: 16.9.0 => 16.9.0
    react-native: ^0.61.5 => 0.61.5

Steps To Reproduce

Provide a detailed list of steps that reproduce the issue.
Issues without reproduction steps or code are likely to stall.
  1. Create an App named MyApp with 1 file
  2. Copy the App to a different folder and rename all occurrences of MyApp with MyApp2

Expected Results

It launches

1 thought on “Cannot create a string longer than 0x3fffffe7 characters in jest-haste-map”

  1. So the problem was that i had a folder where i kept all my assets (logos, banners, psds, …) which was rather big and called _assets. moving that folder a level higher out of the root folder fixed the problem

    EDIT:
    Adding it to the blacklist in metro.config.js allowed me to have it in my project as well.

    const blacklist = require(‘metro-config/src/defaults/blacklist’);
    module.exports = {
    resolver: {
    blacklistRE: blacklist([/_assets\/.*/]),
    },
    };

    thanks to https://stackoverflow.com/questions/41813211/how-to-make-react-native-packager-ignore-certain-directories

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