[bug] Social Login (Universal Wallet) fails with custom EVM chain – Magic RPC Error [-32603]

[txrush-xyz]

Link to minimal reproducible example

https://txrush-xyz.github.io/reown-appkit-custom-evm/

Steps to Reproduce

1. Configure a custom EVM chain using defineChain() in @reown/appkit.

   • chainId: 2201 (0x899)
   • RPC: https://rpc.testnet.stable.xyz

2. Initialize WagmiAdapter with:

   new WagmiAdapter({
   projectId,
   networks: [stableChain],
   ssr: false
   })

3. Connect using:

   • EOA wallet (e.g. MetaMask) → Works correctly.
   • Social Login (Universal Wallet) → Connects successfully.

4. Attempt to send a transaction using the connected Social Login wallet.

5. Observe error:

   W3mFrameLogger
   Magic RPC Error: [-32603] Failed to fetch

Summary

EOA wallets work correctly on the custom chain.

However, when using Social Login (Universal Wallet),
any RPC interaction (e.g. transaction send) fails with:

Magic RPC Error: [-32603] Failed to fetch

Important observations:

• The RPC endpoint is reachable and functional.
  Calling eth_chainId directly returns:
  { "result": "0x899" }

• The issue occurs ONLY with Social Login.

• EOA wallets using the same RPC work correctly.

• No CSP is configured in CloudFront.

• RPC server returns Access-Control-Allow-Origin: *

This suggests Universal Wallet (Magic integration)
may not allow custom chains by default,
or requires internal chain registration/whitelisting.

List of related npm package versions

"@reown/appkit": "1.8.18",
"@reown/appkit-adapter-wagmi": "1.8.18",
"@tanstack/react-query": "^5.56.2",
"react": "^19.2.0",
"react-dom": "^19.2.0",
"viem": "^2.9.20",
"wagmi": "^2.12.15"

Node.js Version

v22.10.0

Package Manager

10.9.0

[linear]

REOWN-4528