relayprotocol · GiselleNessi · Jul 15, 2026 · Jul 1, 2026 · Jul 8, 2026 · Jul 8, 2026
diff --git a/docs.json b/docs.json
@@ -93,6 +93,7 @@
                   "references/api/api_core_concepts/trade-types",
                   "references/api/api_core_concepts/surplus-and-shortage",
                   "references/api/api_core_concepts/handling-errors",
+                  "references/api/api_core_concepts/execution-errors",
                   "references/api/api_core_concepts/contract-compatibility"
                 ]
               },

diff --git a/references/api/api_core_concepts/execution-errors.mdx b/references/api/api_core_concepts/execution-errors.mdx
@@ -0,0 +1,133 @@
+---
+title: "Handling Execution Errors"
+description: "Interpret fill and refund failure reasons returned after a request has been submitted"
+---
+
+Once a request is submitted, execution can still fail during the fill or, if a fill isn't possible, during the refund. These failures are surfaced as `failReason` (fill) and `refundFailReason` (refund) on the request object, distinct from the [quote errors](/references/api/api_core_concepts/handling-errors) returned before a request is ever submitted. This guide outlines the possible fill and refund failure reasons and what each one means.
+
+## Fill Errors
+
+`failReason` explains why a fill did not complete after a request was submitted.
+
+### Deposit & Validation Errors
+
+| Error Code | Description |
+| ---------- | ------------ |
+| `DEPOSIT_CHAIN_MISMATCH` | For strict deposit addresses, the deposit landed on a different chain than the one the address was registered for. |
+| `INCORRECT_DEPOSIT_CURRENCY` | For strict deposit addresses, the token received doesn't match the currency quoted for this request. |
+| `DOUBLE_SPEND` | A second deposit was detected at an address whose first deposit was already processed. |
+| `DEPOSITED_AMOUNT_TOO_LOW_TO_FILL` | The amount deposited is less than the quoted amount needed to complete the swap. |
+| `ORIGIN_CURRENCY_MISMATCH` | The currency detected on origin doesn't match the origin currency specified in the request. |
+| `TTL_EXPIRED` | The request's time-to-live window passed before it could be filled. |
+| `DEPOSIT_CONFIRMATION_TIMEOUT` | The deposit transaction wasn't confirmed within the expected window, so the request timed out and was routed to a refund. |
+| `DEPOSIT_REORGED` | The deposit transaction was removed from the canonical chain by a block reorganization, so the request was failed. |
+| `ORPHANED_DEPOSIT_REFUND` | A deposit at a deposit address couldn't be matched to a fillable request, so the funds were refunded to the depositor. |
+| `BLOCKED_WALLET` | An address associated with the request was flagged by wallet screening at fill time, so the fill was blocked. Funds are not automatically refunded and are subject to compliance review. |
+
+### Solver Capacity & Balance Errors
+
+| Error Code | Description |
+| ---------- | ------------ |
+| `SOLVER_CAPACITY_EXCEEDED` | The solver's available capacity for this route has been exceeded. |
+| `SOLVER_BALANCE_TOO_LOW` | The solver doesn't have enough native tokens or balance to construct the fill transaction. |
+| `SPONSOR_BALANCE_TOO_LOW` | The sponsor covering transaction fees doesn't have sufficient balance. |
+| `INSUFFICIENT_FUNDS_FOR_RENT` | The user's balance isn't enough to cover rent/storage fees (Solana). |
+| `NEGATIVE_NEW_AMOUNT_AFTER_FEES` | After deducting fees, the resulting amount is zero or negative. |
+| `AMOUNT_TOO_LOW_TO_REFUND` | The amount to refund is zero or negative, or below the chain's minimum transfer threshold, so no refund could be issued. |
+| `GASLESS_PERMIT_BALANCE_TOO_LOW` | The balance available from a gasless permit wasn't enough to complete the request, so the funds were refunded. |
+
+### Swap Routing & Pricing Errors
+
+| Error Code | Description |
+| ---------- | ------------ |
+| `NO_QUOTES` | No liquidity providers returned a valid quote for this swap at fill time. |
+| `NO_INTERNAL_SWAP_ROUTES_FOUND` | No internal DEX route was found between the specified currencies on this chain. |
+| `SWAP_IMPACT_TOO_HIGH` | The swap's price impact at fill time exceeds the acceptable threshold. |
+| `INSUFFICIENT_POOL_LIQUIDITY` | The DEX pool doesn't have enough reserves to complete the swap at any price. |
+| `SLIPPAGE` | The swap couldn't complete within the given slippage tolerance. |
+| `TOO_LITTLE_RECEIVED` | The onchain swap executed, but the output amount was below the guaranteed minimum. |
+| `GENERATE_SWAP_FAILED` | Generating the swap transaction (routing, calldata) failed before execution. |
+| `REVERSE_SWAP_FAILED` | The reversal swap used to return funds to the user for a refund failed to execute or quote. |
+
+### Transaction Construction & Gas Errors
+
+| Error Code | Description |
+| ---------- | ------------ |
+| `TRANSACTION_TOO_LARGE` | The serialized transaction exceeds the maximum payload size for the origin chain or RPC. |
+| `SWAP_USES_TOO_MUCH_GAS` | The swap transaction would consume more gas than a single block allows. |
+| `NEW_CALLDATA_INCLUDES_HIGHER_RENT_FEE` | A refreshed permit increased the rent/storage fee beyond the acceptable limit (Solana). |
+| `INVALID_GAS_PRICE` | The submitted gas price is outside acceptable bounds. |
+| `QUOTED_GAS_LIMIT_EXCEEDED` | The gas limit required at fill time was significantly higher than the gas limit quoted, so the fill was aborted. |
+| `JUPITER_INVALID_TOKEN_ACCOUNT` | The token account required for the swap doesn't exist or is invalid (Solana/Jupiter). |
+
+### Onchain Execution & Revert Errors
+
+| Error Code | Description |
+| ---------- | ------------ |
+| `EXECUTION_REVERTED` | The swap contract call reverted during execution. |
+| `TRANSACTION_REVERTED` | The transaction reverted at the blockchain level. |
+| `MISSING_REVERT_DATA` | The transaction reverted, but the reason couldn't be decoded from the returned data. |
+| `CONTRACT_PAUSED` | The target contract is currently paused and not accepting calls. |
+| `TOKEN_NOT_TRANSFERABLE` | The token enforces a non-transferable restriction (for example, a soulbound token). |
+| `TRANSFER_FAILED` | A token transfer reverted at the contract level. |
+| `TRANSFER_FROM_FAILED` | Transferring tokens from the user to the contract failed (for example, insufficient allowance). |
+| `TRANSFER_AMOUNT_EXCEEDS_ALLOWANCE` | The approved allowance is less than the amount being transferred. |
+| `TRANSFER_AMOUNT_EXCEEDS_BALANCE` | The sender's token balance is less than the amount being transferred. |
+| `INSUFFICIENT_NATIVE_TOKENS_SUPPLIED` | The native token value supplied with the transaction is less than required. |
+| `INCORRECT_PAYMENT` | The value or amount sent doesn't match what the swap requires. |
+| `ZERO_SELL_AMOUNT` | The swap was attempted with a zero input amount. |
+| `INVALID_SENDER` | The address executing the swap isn't authorized to do so. |
+| `INVALID_SIGNER` | The signer on the order doesn't match the address expected by the contract. |
+| `DESTINATION_TOKEN_TRANSFER_REJECTED` | A token transfer reverted during the destination-side swap — typically the token itself rejecting the transfer (transfer tax, max wallet/transaction limits, or a blacklist). |
+
+### Order & Signature Errors
+
+| Error Code | Description |
+| ---------- | ------------ |
+| `ORDER_EXPIRED` | The order's expiration timestamp passed before it could be executed. |
+| `ORDER_IS_CANCELLED` | The order was cancelled onchain before it could be filled. |
+| `ORDER_ALREADY_FILLED` | The order was already fully executed and can't be filled again. |
+| `SIGNATURE_EXPIRED` | The signature used for token approval expired before execution. |
+| `INVALID_SIGNATURE` | The provided signature is invalid or doesn't match the expected signer. |
+| `INVALID_NONCE` | The nonce provided has already been used or isn't valid for this signer. |
+| `SEAPORT_INEXACT_FRACTION` | The Seaport order specifies a fractional amount that can't be fulfilled exactly. |
+| `SEAPORT_INVALID_FULFILLER` | The caller isn't an authorized fulfiller for this Seaport order. |
+| `PROTOCOL_DEADLINE_EXPIRED` | The protocol order's deadline expired before the fill could complete, so a no-fill-or-refund was submitted onchain. |
+
+### Account Abstraction Errors
+
+| Error Code | Description |
+| ---------- | ------------ |
+| `ACCOUNT_ABSTRACTION_INVALID_NONCE` | The nonce in the account abstraction user operation is invalid or stale. |
+| `ACCOUNT_ABSTRACTION_SIGNATURE_ERROR` | The account abstraction user operation's signature is invalid. |
+| `ACCOUNT_ABSTRACTION_GAS_LIMIT` | The gas required for account abstraction verification exceeds the allowed limit. |
+
+### NFT Minting Errors
+
+| Error Code | Description |
+| ---------- | ------------ |
+| `MINT_NOT_ACTIVE` | The NFT mint phase isn't currently active. |
+| `ERC_1155_TOO_MANY_REQUESTED` | The quantity requested exceeds the contract's allowed batch size. |
+| `MINT_QUANTITY_EXCEEDS_MAX_PER_WALLET` | The wallet has already minted the maximum quantity allowed. |
+| `MINT_QUANTITY_EXCEEDS_MAX_SUPPLY` | The requested quantity would exceed the collection's maximum supply. |
+
+### Other
+
+| Error Code | Description |
+| ---------- | ------------ |
+| `FLUID_DEX_ERROR` | The Fluid DEX protocol returned an error during the swap. |
+| `MANUAL_ADMIN_REFUND` | The request was manually refunded by the Relay team via an admin action. |
+| `UNKNOWN` | The fill failed for a reason that didn't match a known error pattern. |
+| `N/A` | The fill completed without failure. |
+
+## Refund Errors
+
+`refundFailReason` explains why a refund could not be completed after a fill failed. This field defaults to `N/A` when no refund failure has occurred.
+
+| Error Code | Description |
+| ---------- | ------------ |
+| `AMOUNT_TOO_LOW_TO_REFUND` | The amount to refund is zero or negative, or below the chain's minimum transfer threshold, so no refund could be issued. |
+| `NEGATIVE_NEW_AMOUNT_AFTER_FEES` | After deducting fees, the resulting amount is zero or negative. |
+| `SWAP_CURRENCY_NOT_ON_ORIGIN` | The swap's output currency isn't available to bridge back to the origin chain, so the refund can't be issued in the original currency. |
+| `REFUND_RECIPIENT_IS_VASP` | The refund recipient was identified as a Virtual Asset Service Provider (VASP), which requires manual review before the refund can be issued. |
+| `N/A` | No refund failure has occurred. |
diff --git a/references/api/api_core_concepts/handling-errors.mdx b/references/api/api_core_concepts/handling-errors.mdx
@@ -5,6 +5,8 @@ description: "Interpret and recover from quote errors in your integration"
 
 When calling the `/quote/v2` endpoint, various errors may be returned depending on request conditions, user input, or internal routing logic. This guide outlines the possible error codes, their meanings, and how to handle them.
 
+<Tip>Looking for errors that occur after a request is submitted? See [Handling Execution Errors](/references/api/api_core_concepts/execution-errors) for fill and refund failure reasons.</Tip>
+
 ## Expected Errors
 
 These are known validation and routing issues that developers should gracefully handle in their integrations: