diff --git a/modules/sdk-coin-sui/src/lib/customTransaction.ts b/modules/sdk-coin-sui/src/lib/customTransaction.ts
index 93137d8833..46a0961426 100644
--- a/modules/sdk-coin-sui/src/lib/customTransaction.ts
+++ b/modules/sdk-coin-sui/src/lib/customTransaction.ts
@@ -8,11 +8,12 @@ import {
 import { Transaction } from './transaction';
 import { BaseCoin as CoinConfig } from '@bitgo/statics';
 import utils from './utils';
-import { BaseKey, InvalidTransactionError, TransactionRecipient, TransactionType } from '@bitgo/sdk-core';
+import { BaseKey, InvalidTransactionError, Recipient, TransactionRecipient, TransactionType } from '@bitgo/sdk-core';
 import { UNAVAILABLE_TEXT } from './constants';
 
 export class CustomTransaction extends Transaction<CustomProgrammableTransaction> {
   private _rawTransaction: string;
+  private _recipients: Recipient[];
 
   constructor(_coinConfig: Readonly<CoinConfig>) {
     super(_coinConfig);
@@ -70,13 +71,13 @@ export class CustomTransaction extends Transaction<CustomProgrammableTransaction
       return;
     }
 
-    const recipients = utils.getRecipients(this._suiTransaction);
-    this._outputs = recipients.map((recipient, index) => ({
+    this._recipients = utils.getRecipients(this._suiTransaction);
+    this._outputs = this._recipients.map((recipient, index) => ({
       address: recipient.address,
       value: recipient.amount,
       coin: this._coinConfig.name,
     }));
-    const totalAmount = recipients.reduce((accumulator, current) => accumulator + Number(current.amount), 0);
+    const totalAmount = this._recipients.reduce((accumulator, current) => accumulator + Number(current.amount), 0);
 
     this._inputs = [
       {
diff --git a/modules/sdk-coin-sui/src/lib/customTransactionBuilder.ts b/modules/sdk-coin-sui/src/lib/customTransactionBuilder.ts
index 83d58c0e32..d8cac02b4f 100644
--- a/modules/sdk-coin-sui/src/lib/customTransactionBuilder.ts
+++ b/modules/sdk-coin-sui/src/lib/customTransactionBuilder.ts
@@ -2,7 +2,7 @@ import { TransactionBuilder } from './transactionBuilder';
 import { CustomProgrammableTransaction, SuiTransaction, SuiTransactionType } from './iface';
 import { BaseCoin as CoinConfig } from '@bitgo/statics';
 import { CustomTransaction } from './customTransaction';
-import { BuildTransactionError, TransactionType } from '@bitgo/sdk-core';
+import { BuildTransactionError, InvalidTransactionError, TransactionType } from '@bitgo/sdk-core';
 import { Transaction } from './transaction';
 import assert from 'assert';
 import utils from './utils';
@@ -63,6 +63,10 @@ export class CustomTransactionBuilder extends TransactionBuilder<CustomProgramma
   }
 
   /**
+   * Currently custom tx only allows a combination of 3 types of SUI transactions:
+   * 1. SplitCoins
+   * 2. TransferObjects
+   * 3. MoveCall
    * @inheritdoc
    */
   validateTransaction(transaction: CustomTransaction): void {
@@ -70,11 +74,16 @@ export class CustomTransactionBuilder extends TransactionBuilder<CustomProgramma
       return;
     }
     this.validateTransactionFields();
-
-    // Check all the transaction types are supported
-    this.transaction.suiTransaction.tx.transactions.forEach((tx) => {
-      utils.getSuiTransactionType(tx);
-    });
+    try {
+      this.transaction.suiTransaction.tx.transactions.forEach((tx) => {
+        utils.getSuiTransactionType(tx);
+      });
+    } catch (e) {
+      if (e instanceof InvalidTransactionError) {
+        throw new BuildTransactionError(e.message);
+      }
+      throw e;
+    }
   }
 
   /**
diff --git a/modules/sdk-coin-sui/src/lib/utils.ts b/modules/sdk-coin-sui/src/lib/utils.ts
index a3a86c5587..00e59df2de 100644
--- a/modules/sdk-coin-sui/src/lib/utils.ts
+++ b/modules/sdk-coin-sui/src/lib/utils.ts
@@ -214,10 +214,10 @@ export class Utils implements BaseUtils {
         } else if (command.target.endsWith(MethodNames.StakingPoolSplit)) {
           return SuiTransactionType.CustomTx;
         } else {
-          throw new InvalidTransactionError(`unsupported target method`);
+          throw new InvalidTransactionError(`unsupported target method ${command.target}`);
         }
       default:
-        throw new InvalidTransactionError(`unsupported transaction kind`);
+        throw new InvalidTransactionError(`unsupported transaction kind ${command.kind}`);
     }
   }