# Verifying Paymaster Common Errors

`Insufficient Pimlico balance for sponsorship, please top up`

This error means that you do not have enough Pimlico balance to sponsor the User Operation. Testnet User Operations are free to sponsor. To sponsor User Operations on a mainnet chain, add a card or a balance on the [Pimlico dashboard](https://dashboard.pimlico.io). If you have already reached your overdraft limit and need it raised, [reach out to us](https://t.me/pimlicoHQ).

`invalid 'apikey' query parameter` / `missing 'apikey' query parameter`

This error means that you have not provided a valid API key in the query parameters. You can [create an API key here](/guides/create-api-key).

`chain XYZ is not supported`

This error means that the chain you are trying to sponsor a User Operation on is not supported by Pimlico. You can find the list of supported chains [here](/guides/supported-chains). If there is a chain we do not yet support that you would like to see added, [reach out to us](https://t.me/kristofgazso).