Using BigNumber.from with result of formatUnits index.js? cause Error invalid BigNumber string

[Ding-Fan]

Result of formatUnits is '1.0'
https://docs.ethers.io/v5/api/utils/display-logic/#unit-conversion
It isn't BigNumberish
https://docs.ethers.io/v5/api/utils/bignumber/#BigNumberish

string
A HexString or a decimal string, either of which may be negative.

// node_modules/@ethersproject/bignumber/src.ts/bignumber.ts

    static from(value: any): BigNumber {
        if (value instanceof BigNumber) { return value; }

        if (typeof(value) === "string") {
            if (value.match(/^-?0x[0-9a-f]+$/i)) {
                return new BigNumber(_constructorGuard, toHex(value));
            }

            if (value.match(/^-?[0-9]+$/)) {
                return new BigNumber(_constructorGuard, toHex(new BN(value)));
            }

            return logger.throwArgumentError("invalid BigNumber string", "value", value);
        }
...

[ricmoo]

That’s correct. formatUnits is designed to take a value and convert it to a string for the purposes of display logic. You need to use parseUnits to take a decimal or unit-ed value and convert it to a BigNumber.