I got some error when using Polkadot{js} API. what's wrong? should I update the version of package?

import { BN, BN_BILLION, BN_HUNDRED, BN_MILLION, BN_QUINTILL, bnToBn, bnToHex, bnToU8a, formatBalance, formatNumber, hexToBn, isBigInt, isBn, isFunction, isHex, isNumber, isObject, isString, isU8a, u8aToBn, u8aToNumber } from '@polkadot/util';
SyntaxError: The requested module '@polkadot/util' does not provide an export named 'u8aToNumber'
    at ModuleJob._instantiate (node:internal/modules/esm/module_job:123:21)
    at async ModuleJob.run (node:internal/modules/esm/module_job:189:5)
    at async Promise.all (index 0)
    at async ESMLoader.import (node:internal/modules/esm/loader:530:24)
    at async importModuleDynamicallyWrapper (node:internal/vm/module:438:15) {
  page: '/'

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  • I could solve the issue by deleting node_modules and install again
    – Steve
    Feb 13, 2023 at 5:11
  • If deleting your node_modules and installing again worked it was probably a version issue. You can create an answer to your question an mark it as solved
    – Alex Bean
    Feb 13, 2023 at 9:08

2 Answers 2


Polkadot-js has a pretty strict dependency tree outline where versions of different @polkadot/* packages need to match the root of @polkadot/api.

For example:

@polkadot/api -> v9.14.1 requires @polkadot/util -> v10.4.1 So if you are using v9.14.1 of the API, any package you consume from the polkadot-js/common (i.e. @polkadot/util-crypto, @polkadot/keyring, etc.) repository should also be v10.4.1.

This will ensure that there is no conflict in package versions and the above error won't happen. Also as a side note, updating to the latest version of each package will ensure they match, as releases will be in sync with each other.


all what I had to do was update the version of packages so if you meet this error, plz try to delete node_module and yarn install again

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