1. Exit Codes

• An exit code is a 16-bit unsigned integer which ranges between 0 to 65535 (or 2¹⁶-1).
• The best practice is to allocate 0 to 127 codes for Func Exit Codes, 128 to 255 for Tact Exit Codes, and 256 to 65535 for developer-defined Exit Codes.

Where to observe the list of all auto-generated exit codes in your project?

• The Tact Compiler collects all exit codes at the end of a *.md file and you can track them in the directory along the path "./ProjectFolder/build/ProjectName/tact_ProjectName.md"

How to observe a thrown exit code?

• In TACT, it's not wise to print the transactions to see the results because they are not easy to read. If you want to see the exit code of a transaction, use the below template in your Typescript local tests:

const sender = await blockchain.treasury('sender');
const result = await contractName.send(sender.getSender(), { value: toNano('0.05'), }, { transactionData });
expect(result.transactions).toHaveTransaction(
    { from: sender.address, to: contractName.address, exitCode: YOUR_DESIRED_EXIT_CODE }
    )

•   First line defines the sender.
•   Second line sends the transaction.
•   In the third line, you check if the result has a transaction from sender to your contract with your desired exit code.

Keywords:

• Compute phase: in this phase, TVM is executing the contract (see below) and the result of the contract execution is an aggregation of exit_code, actions (serialized list of actions), gas_details, new_storage and some others.
• Action phase: if the compute phase was successful, in this phase, actions from the compute phase are processed. In particular, actions may include sending messages, updating the smart contract code, updating the libraries, etc. Note that some actions may fail during processing (for instance, if we try to send message with more TON than the contract has), in that case the whole transaction may revert or this action may be skipped (it depends on the mode of the actions, in other words, the contract may send a send-or-revert or try-send-if-no-ignore type of message).
• Tact (Compiler): It's a new keyword similar to normal compute phase but, it is checked in transpiled FunC code.

2. Exit Code Examples

2.1 Compute Phase

0: Successful execution (compute phase)
This exit code means that the Compute Phase of the transaction was completed successfully.

Example :

return ;

4: Integer overflow (compute phase)
In TVM, integer can be in the range -2²⁵⁶ < x < 2²⁵⁶. If the value during the calculation went beyond this range, then 4 exit code is thrown.

Example :

self.id = 1; // force not to ignore it by using storage variables
repeat(256) {
    self.id = 2 * self.id;
}

5: Integer out of expected range (compute phase)
If the integer value went beyond the expected range, then 5 exit code is thrown. For example, if a negative value was used in the .store_uint() function. In Tact, there are some other new situations such as:
1- As you know, you can define more limited integers in Tact (integers with less than 257 bits). If you try to store a number in this kind of integers and the number doesn't fit to this limited range, you will face this exit code.
2- according to storeUint(self: Builder, value: Int, bits: Int) function, it's not possible to use storeUint(0, 257) because 0 ≤ bits ≤ 256.

Example :

// option 1 -> id: Int as uint32
self.id = 1; // force not to ignore it by using storage variables
repeat(32) {
    self.id = 2 * self.id;
}
// option 2 -> according to storeUint(self: Builder, value: Int, bits: Int) function, it's not possible to use storeUint(0, 1024) because 0 ≤ bits ≤ 256
let s: Slice = beginCell().storeUint(0, 257).asSlice();

8: Cell overflow (compute phase)
A cell has the capacity to store 1023 bits of data and 4 references to other cells. If you try to write more than 1023 bits or more than 4 references, 8 exit code is thrown.

Example :

// according to storeUint(self: Builder, value: Int, bits: Int) function, it's not possible to use storeUint(0, 1024) because 0 ≤ bits ≤ 256
let s: Slice = beginCell().storeUint(0, 256).storeUint(0, 256).storeUint(0, 256).storeUint(0, 256).asSlice();       

9: Cell underflow (compute phase)
If you try to read more data from a slice than it contains, then 9 exit code is thrown.

Example :

let s: Slice = emptySlice();
self.id = s.loadUint(1); // force not to ignore it by using storage variables

13: Out of gas error (compute phase)
If there isn't enough TON to handle compute phase, this error is thrown. During processing, the NOT operation is applied to this value, which changes this value to -14. This is done so that this exit code cannot be faked using the throw function, since all such functions accept only positive values for the exit code as it was discussed previously.

Example :

repeat(10000) {
    self.id = self.id + 1;
}

2.2 Action Phase

34: Action is invalid or not supported (action phase)
This exit code is responsible for most of the errors when working with actions: invalid message, incorrect action, and so on.

Example :

nativeSendMessage(emptyCell(), 0);

37: Not enough TON (action phase)
It means that there isn't enough TON to send the specified amount of it.

Example :

send(SendParameters{to: context().sender, value: ton("10")});

2.3 Tact (Compiler)

130: Invalid incoming message
When you send a message to a contract, the first 32 bits of message body is the op code. It determines the operation that must be done. In FunC, if no op code is found, 0xffff will be thrown. In Tact, 130 exit code will be thrown.

Example :
First, define an empty contract like below:

contract Fireworks {
 
    init(){
 
    }
}

Then, send a message to this contract. Because no suitable operation is found, you will get this exit code.

132: Access denied
First, you should import and inherit from Ownable Trait. After it, your contract will have an owner. You can ask for a check by calling self.requireOwner(); in your functions. It will ensure that only the owner can send message to your contract.

Example :

import "@stdlib/deploy";
import "@stdlib/ownable";
 
message FakeLaunch {
 
}
 
contract Fireworks with Deployable, Ownable {
    owner: Address;
 
    init(){
        self.owner = sender();
    }
 
    receive(msg: FakeLaunch){
        self.requireOwner();
    }
}
 
fun requireOwner() {
        nativeThrowUnless(132, sender() == self.owner);
}

133: Contract stopped
The stoppable trait allows to stop the contract. If you send a message to a stopped contract, and the contract asks for a check by running self.requireNotStopped();, this exit code will be thrown. In the current version of Tact, 40368 exit code will be thrown instead of 133.

Example :

import "@stdlib/deploy";
import "@stdlib/ownable";
import "@stdlib/stoppable";
 
message FakeLaunch {
 
}
 
contract Fireworks with Deployable, Ownable, Stoppable {
    owner: Address;
    stopped: Bool;
 
    init(){
        self.owner = sender();
        self.stopped = false;
    }
 
    receive(msg: FakeLaunch){
        self.stopped = true;
        self.requireNotStopped();
    }
}
 
fun requireNotStopped() {
        require(!self.stopped, "Contract stopped");
}

134: Invalid argument
This will be thrown by the below FunC function(in the last part of a bunch of if conditions). This function reads something from Base64. If the input characters don't fit into base64 chars, you will encounter this exit code.

Example :

let code: Slice = beginCell().storeUint(0, 8).asSlice().fromBase64();
// 0 is not a valid ASCII code so it cannot be converted to Base64

135: Code of a contract was not found
It will check the return flag of a search on the dictionary keys.

Example :

// copy & paste the below line in wrapper file(../build/ContractName/tact_ContractName.ts) instead of the second line of ContractName_init() function - this is a dictionary containing another smart contract code which leads to 135 exit code
// const __system = Cell.fromBase64('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');
let ctx: Context = context();
let fireworks_init: StateInit = initOf Fireworks(0);

136: Invalid address
1- In TON, all addresses are 267 bits. If you violate this rule, you will face this exit code.
2- Currently, TON only supports two chain id. 0 for basechain and -1 for masterchain. If you address isn't from basechain, 136 exit code will be thrown.

Example :

// fun newAddress(chain: Int, hash: Int): Address;
// creates a new address from chain and hash values.
let zeroAddress: Address = newAddress(1, 0); // invalid-chain zero address

137: Masterchain support is not enabled for this contract
Currently, TON only supports two chain id. 0 for basechain and -1 for masterchain. Tact only supports basechain and if you address is from masterchain, 137 exit code will be thrown.

Example :

// fun newAddress(chain: Int, hash: Int): Address;
// creates a new address from chain and hash values.
let zeroAddress: Address = newAddress(-1, 0); // master-chain zero address