Error: account validation failed: AA21 didn't pay prefund

Getting this error while making a gasless txn for account abstraction.

based on the limited information to my guess ,this error usually occurs in two situations

  1. The contract on which you are executing the transaction is not whitelisted, if the contract is infact whitelisted then the function being called in the transaction is not whitelisted.
  2. Your paymaster is not initialized correctly

Hi, got the same issue today. error Error: account validation failed: AA21 didn't pay prefund
I made sure that contract and the particular function is whitelisted.
How to know whether the paymaster init correctly. could there be anyother issue, like node error?