Knit API Documentation

CPN Troubleshooting

Common issues and solutions when integrating CPN with Knit's Managed Signing API.

"Failed to sign transaction" from Managed Signing

Cause: Transaction is missing required fields (fees, gas, or nonce).

Solution:

• Ensure the transaction includes EIP-1559 fields (maxFeePerGas, maxPriorityFeePerGas) or legacy fields (gasPrice)
• Include gas limit
• Include nonce
• Verify RPCs are configured for the target network to enable auto-fill

"POLICY_DENIED" Error

Cause: The signing request violates your policy rules.

Solutions:

"Invalid typed data" Error

Cause: The EIP-712 typed data format is incorrect.

Solution:

• Use Circle's messageToBeSigned exactly as provided
• Do not modify or camelCase keys in types or message
• Ensure the JSON is valid (no comments, trailing commas)

Permit2 Approval Transaction Fails

Cause: Insufficient gas or incorrect parameters.

Solutions:

• Ensure wallet has enough native token (MATIC/ETH) for gas
• Verify the USDC token address is correct for your network
• Verify the Permit2 contract address is correct
• Check that the approval amount is valid

Signature Rejected by Circle

Cause: Signature doesn't match expected format or data.

Solutions:

• Verify you're using the exact messageToBeSigned from Circle
• Ensure the signing wallet address matches what Circle expects
• Check that the wallet has completed the Permit2 approval
• Verify the network matches (e.g., both on Polygon)

Request Body Validation Errors

Cause: Invalid JSON or missing required fields.

Solutions:

• JSON request bodies must not include comments
• All required fields must be present
• Use correct data types (strings for addresses, numbers for nonce)
• Ensure walletId is the local ID from Knit, not an external ID

Network Mismatch

Cause: Using wrong network identifier.

Supported Production Networks:

• MATIC_MAINNET (Polygon)
• ETHEREUM_MAINNET
• BSC_MAINNET
• BASE_MAINNET

Supported Testnet Networks (Sandbox/Dev only):

• MATIC_AMOY (Polygon Amoy testnet - commonly used for CPN testing)

Do not use ETH_MAINNET - use ETHEREUM_MAINNET instead.

Auto-Fill Not Working

Cause: RPC not configured for the target network.

Solution:

• Contact Knit support to verify RPC configuration
• Alternatively, provide txOverrides with manual gas values
• For broadcast: false, you may need to estimate gas externally

Common Contract Addresses

Contact Circle for the official addresses for your integration. These are for reference only:

Getting Help

If you continue to experience issues:

1. Check the audit logs: GET /api/v1/managed-signing/audit?requestId=<request-id>
2. Verify your policy configuration: GET /api/v1/managed-signing/policies/<policy-id>
3. Contact Knit support with:
   • Request ID
   • Error message
   • Request payload (sanitized)
   • Network and wallet address