# Limitations
When making requests to Backpack in Establishing a Connection, Sending a Transaction, or Signing a Message, Backpack may respond with an error.
## Errors
The following is a list of all possible error codes and their meanings. These error messages are inspired by Ethereum's [EIP-1474](https://eips.ethereum.org/EIPS/eip-1474#error-codes) and [EIP-1193](https://eips.ethereum.org/EIPS/eip-1193#provider-errors).
| Code | Title | Description |
| ------ | -------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| 4900 | Disconnected | Backpack could not connect to the network. |
| 4100 | Unauthorized | The requested method and/or account have not been authorized by the user. |
| 4001 | User Rejected Request | The user rejected the request through Backpack. |
| -32000 | Invalid Input | Missing or invalid parameters. |
| -32002 | Requested resource not available | This error occurs when an app attempts to submit a new transaction while Backpack's approval dialog is already open for a previous transaction.
Only one approve window can be open at a time. Users should approve or reject their transactions before initiating a new transaction.
|
| -32003 | Transaction Rejected | Backpack does not recognize a valid transaction. |
| -32601 | Method Not Found | Backpack does not recognize the method. |
| -32603 | Internal Error | Something went wrong within Backpack. |
Typically, these errors will be easily parseable and have both a code and an explanation. For example:
```
try {
await window.solana.signMessage();
} catch (err) {
// {code: 4100, message: 'The requested method and/or account has not been authorized by the user.'}
}
```