This error happen in blockchain wallet when u set the fees to the lowest fee possible which is "1" or when u make consecutive transactions in such speed
Not so sure about why it errors when setting to lowest fee but the latter is probably to prevent double spending that trigger them even though the amount might not actually the same as long it covers a short period of time to execute the sending process.
Why are you even still using blockchain wallet in the first place.
It's because blockchain.com has organically funnels any new users while using google when searching bitcoin wallets. OP might register when he still newbie or still newbie in this space
I suggest to OP that listen to those guys suggesting above. Electrum is way more better to use as a wallet.