Metamask Internal JSON-RPC Error Explained & Solved (Fix Now)

I was trying to mint a hot NFT on the Polygon network last Tuesday. Everything was ready. I clicked “Confirm.” Then, the dreaded red box appeared: Internal JSON-RPC Error.

My heart sank. I thought I lost my funds. I thought my wallet was compromised. It wasn’t. After three hours of digging through GitHub threads and dev logs, I realized this error is just the Web3 version of a “404 Not Found” or a bad phone connection. It’s annoying, but it’s fixable.

If you are seeing this right now, stop clicking “Confirm.” You are likely just wasting gas. Let’s walk through exactly what is happening under the hood and how to get your transactions moving again.

Quick Summary

• The Internal JSON-RPC Error usually means your wallet and the blockchain node aren’t speaking the same language.
• Most fixes involve resetting your account nonce, switching RPC endpoints, or bumping up your gas fees.
• It is rarely a hack. It is almost always a technical glitch between Metamask and the network provider.

What Exactly is a JSON-RPC Error?

To fix this, you have to understand how Metamask works. Metamask doesn’t actually “hold” your crypto. It’s just a window. The crypto lives on the blockchain. To see your balance or send a transaction, Metamask talks to a “Node.”

This conversation happens via JSON-RPC (Remote Procedure Call). Think of it as a waiter in a restaurant. You (the user) tell the waiter (JSON-RPC) what you want to eat (the transaction). The waiter takes that message to the kitchen (the blockchain node).

When you get an “Internal Error,” it means the waiter came back and said, “The kitchen is on fire, and I don’t know why.” The node encountered a problem it couldn’t explain. It’s a catch-all error for “something went wrong back there.”

Common Causes for the Internal JSON-RPC Error

I’ve tracked hundreds of these errors. They usually fall into one of these buckets:

• The Nonce Issue: Your transaction numbers are out of sync.
• Gas Problems: You didn’t offer enough money to the miners/validators.
• RPC Congestion: The node provider (like Infura) is overloaded.
• Network Mismatch: You’re trying to send a BSC transaction while Metamask is set to Ethereum.
• Smart Contract Bugs: The dapp you are using has bad code.

Step 1: The Nuclear Fix (Reset Your Account)

Don’t worry. “Resetting” your account does NOT delete your money or your seed phrase. It simply wipes your transaction history in Metamask. This is the #1 fix for the Internal JSON-RPC error.

Why? Because of the Nonce. Every transaction from your wallet has a number (0, 1, 2, 3…). If transaction #5 gets stuck, transaction #6 cannot happen. Metamask gets confused and throws an internal error. Resetting clears the “stuck” line.

How to do it:

1. Open Metamask and click your account icon (the colorful circle).
2. Go to Settings.
3. Click on Advanced.
4. Scroll down and hit Clear activity tab data (formerly “Reset Account”).
5. Confirm the choice.

Try your transaction again. In 80% of cases, this fixes it instantly.

Step 2: Check Your Gas and EIP-1559 Settings

Sometimes the “Internal Error” is just the node saying, “You’re too cheap.” Since the London Hard Fork, Ethereum uses EIP-1559. This changed how gas works. You now have a Base Fee and a Priority Fee.

If you are using a network like Polygon or Avalanche, gas prices can spike 100x in a second. If Metamask suggests a gas price that is lower than the current network minimum, the node will reject it with an internal error.

The Fix: When the Metamask window pops up, click “Market” (the gas estimation). Switch it to “Aggressive.” If that still fails, click “Advanced” and manually bump the Max Fee and Priority Fee. Give the validators a reason to care about your transaction.

Step 3: Switch Your RPC Endpoint (The “Chainlist” Method)

Most people use the default RPCs that come with Metamask. For Ethereum, that’s Infura. For Polygon, it’s their public endpoint. These get crowded. When millions of people try to mint the same NFT, the node crashes.

I saw this happen during the Bored Ape Otherside land sale. The nodes just quit. To fix this, you need a private or alternative “phone line” to the blockchain.

How to switch:

1. Go to Chainlist.org.
2. Connect your wallet.
3. Search for the network you’re using (e.g., “Polygon Mainnet”).
4. Look for endpoints with green bars (low latency).
5. Click “Add to Metamask.”

By switching from a crowded public node to a fresh one (like Alchemy or Ankr), the Internal JSON-RPC error often vanishes.

Step 4: Hardware Wallet Issues (Ledger and Trezor)

If you use a Ledger, the Internal JSON-RPC error is a frequent guest. It usually happens because the Ledger Live app is fighting with the browser extension.

Here is the catch: Chrome updated how it handles “HID” (Human Interface Devices). This broke the old way Metamask talked to Ledger.

The Fix: 1. Ensure your Ledger is plugged in and the “Ethereum” app is open on the device. 2. Make sure “Blind Signing” is enabled in the Ledger app settings. 3. If you’re on Chrome, try switching to the Brave Browser or Firefox. They often handle the bridge better. 4. Close Ledger Live on your desktop. It competes for the connection.

Step 5: The Slippage Trap on Decentralized Exchanges

Are you getting this error on Uniswap, PancakeSwap, or SushiSwap? It might not be a wallet error at all. It’s likely Slippage.

If you are trying to buy a volatile coin and the price moves 2% while you are clicking “Confirm,” the transaction will fail. The smart contract throws an error, and Metamask translates that as an Internal JSON-RPC Error.

The Fix: Click the gear icon on the swap interface. Increase your slippage tolerance to 3% or 5%. It’s risky, but it stops the transaction from reverting.

Section 6: Network-Specific Quirks (Polygon, BSC, and L2s)

Not all blockchains are built the same. I’ve noticed specific patterns with different chains:

Polygon (MATIC)

Polygon is notorious for this error. Their public RPC (polygon-rpc.com) is often under attack or congested. If you see the error here, 100% switch your RPC. Use a provider like 1rpc.io or POKT.

Binance Smart Chain (BSC)

On BSC, the error usually means you don’t have enough BNB for gas. Even if you have $1,000 in USDT, you need BNB to pay the “toll.” Metamask sometimes shows a generic internal error instead of saying “Insufficient Funds.”

Arbitrum and Optimism (Layer 2s)

These use “Sequencers.” If the sequencer is lagging, your transaction gets stuck in a pending state. Resetting your account (Step 1) is almost always the solution here.

Step 7: Check for Extension Conflicts

I once spent an hour debugging a friend’s wallet, only to find out he had Phantom and Metamask both trying to “inject” into the same website. They were fighting for control of the browser’s window.ethereum object.

If you have multiple wallets installed (Coinbase Wallet, Trust Wallet, Phantom), disable the ones you aren’t using. Right-click the extension icon -> Manage Extensions -> Toggle off. Restart your browser. This cleans up the communication path.

Advanced Troubleshooting: Using the Developer Console

If you’ve tried everything and it’s still broken, we need to see what the node is actually saying. This sounds technical, but it’s easy.

1. Right-click anywhere on the page where you’re getting the error.
2. Click Inspect.
3. Click the Console tab.
4. Look for red text.

You might see something like “execution reverted: out of gas” or “replacement transaction underpriced.” This tells you exactly what to fix. If it says “out of gas,” you need to increase your gas limit manually in Metamask’s “Edit” section.

Why Does This Keep Happening? (The Industry Reality)

Let’s be honest: Web3 is still in the “dial-up” phase. The infrastructure is fragmented. Companies like Infura and Alchemy do most of the heavy lifting, but they are centralized points of failure. When they hiccup, we get JSON-RPC errors.

We are also dealing with MEV (Maximal Extractable Value). Bots are constantly front-running transactions. This creates massive spikes in network traffic that the standard RPC nodes can’t always handle. When a bot outbids you for a block space, your transaction might get kicked back with an internal error.

Prevention: How to Avoid Future Errors

You can’t stop the blockchain from being busy, but you can prepare your wallet.

• Keep a Gas Buffer: Always leave at least $20 worth of the native token (ETH, BNB, MATIC) in your wallet. Never “Max out your spending.
• Use a Custom RPC: Don’t wait for a crash. Set up a free account on Alchemy or Infura and get your own private API key. It’s faster and more stable.
• Update Metamask: The team releases fixes for these errors constantly. Check the Chrome Web Store to ensure you are on the latest version.
• Clear Cache Regularly: Browser bloat can slow down the extension’s response time.

The “Internal JSON-RPC Error” Checklist

Before you panic, run through this list in order:

1. Refresh the Dapp: Sometimes the website just loses its connection to Metamask.
2. Reset Account: Settings > Advanced > Clear activity tab data.
3. Check Gas: Switch to “Aggressive” or manual high fees.
4. Switch RPC: Use Chainlist to find a better node.
5. Check Balance: Do you actually have enough for the fee?
6. Restart Browser: The old “turn it off and on again” still works in 2026.

Final Thoughts from the Newsroom

The Metamask Internal JSON-RPC error is a symptom of a growing ecosystem. It’s a sign that the network is busy and the tools are still catching up. It is rarely a sign of a security breach. In my years covering tech, I’ve seen these “handshake” errors in every major industry transition from early internet protocols to the first cloud computing stacks.

Don’t let the red box scare you. Most of the time, the blockchain is just telling you to wait a minute or pay a little more for the ride. Follow the steps above, and you’ll be back to swapping and minting in no time.

Still stuck? If none of this worked, the problem might be with the Smart Contract itself. Check the project’s Discord or Twitter. If everyone is complaining, it’s not you, it’s them. Sit back and wait for the devs to push a fix.