Metamask Configuration Error: Adding Hardhat to Network

There are several common errors that can occur when setting up a local blockchain network to use with Metamask hardhat. One such issue is related to incorrect RPC URLs. In this article, we will look at what causes the error and provide detailed solutions to resolve it.

Error Message:

The error message usually looks like this:

New RPC URL:

Chain ID: 31337

Failed to retrieve string ID. Is the RPC URL correct?

Error Explanation

The error is caused by a misunderstanding of how Metamask resolves RPC URLs. » indicates that the RPC server is running on the local machine, which is fine for testing purposes. However, if you are using hardhat to install and interact with the network, you will need to specify the correct RPC URL.

The issue is likely caused by one of two reasons:

• Invalid string identifier: The error message indicates that there was a problem retrieving the string identifier from Metamask. This is unlikely because it is a standard parameter required for RPC connections.

• RPC server not running: In some cases, the RPC server may not be running or accessible at the specified URL. This can be caused by various reasons, such as network issues, authorization errors, or configuration errors.

Step-by-step solutions:

To resolve this issue, follow these steps:

1. Verify that the RPC server is running

Make sure that the Metamask instance is configured to run an RPC server at You can verify this by checking your metamask settings under
Network >
RPC URL

.

If you are using a custom RPC URL, make sure it is correct and matches the address in the error message.

2. Check for network issues

Try connecting to your local blockchain network using You can do this by copying the RPC URL from your Metamask instance:

wss://127.0.0.1:8545/

If the issues persist, try restarting your RPC server or checking for network connectivity issues.

3. Check the string identifier

Double-check that the string identifier is correct in your hardhat configuration file (usually hardhat.config.js or package.json). Make sure it matches the value given in the error message (31337).

If you are still unsure about the string identifier, consider using a different RPC URL or double-check your metamask settings.

4. Update your hardhat configuration

If none of the above steps resolve the issue, try updating your hardhat configuration file to use the correct RPC URL and string identifier:

const { hardhatConfig } = require('./hardhat.config');
module.exports = hardhatConfig;

Following the steps below you should be able to resolve the «Adding Hardhat as Network» error in your Metamask configuration.