Compiler Exceptions

Vyper raises one or more of the following exceptions when an issue is encountered while compiling a contract.

Whenever possible, exceptions include a source highlight displaying the location of the error within the code:

vyper.exceptions.VariableDeclarationException: line 79:17 Persistent variable undeclared: highstBid
     78     # If bid is less than highest bid, bid fails
---> 79     if (value <= self.highstBid):
     80         return False
exception ArgumentException

Raises when calling a function with invalid arguments, for example an incorrect number of positional arguments or an invalid keyword argument.

exception CallViolation

Raises on an illegal function call, such as attempting to call between two public functions.

exception ArrayIndexException

Raises when an array index is out of bounds.

exception ConstancyViolation

Raises when attempting to perform a modifying action within a constant context. For example, writing to storage in a @constant function or modifying a constant variable.

exception EventDeclarationException

Raises when an event declaration is invalid.

exception EMVVersionException

Raises when a contract contains an action that cannot be performed with the active EVM ruleset.

exception FunctionDeclarationException

Raises when a function declaration is invalid.

exception InterfaceViolation

Raises when an interface is not fully implemented.

exception InvalidAttribute

Raises on a reference to an attribute that does not exist.

exception InvalidLiteral

Raises when attempting to use a literal value where the type is correct, but the value is still invalid in some way. For example, an address that is not check-summed.

def foo():
    bar: address = 0xdeadbeefdeadbeefdeadbeefdeadbeefdeadbeef
exception InvalidOperation

Raises when using an invalid operator for a given type.

def foo():
    a: string[10] = "hello" * 2

This example raises InvalidOperation because multiplication is not possible on string types.

exception InvalidReference

Raises on an invalid reference to an existing definition.

baz: int128

def foo():
    bar: int128 = baz

This example raises InvalidReference because baz is a storage variable. The reference to it should be written as self.baz.

exception InvalidType

Raises when attempting to assign to an invalid type, or perform an action on a variable of the wrong type.

bids: map(address, Bid[128])
bidCounts: map(addres, int128)

In the above example, the variable type address is misspelled. Any word that is not a reserved word, and declares a variable type will return this error.

vyper.exceptions.InvalidTypeException: line 28:15 Invalid base type: addres
         27 bids: map(address, Bid[128])
    ---> 28 bidCounts: map(addres, int128)
exception JSONError

Raises when the compiler JSON input is malformed.

exception NamespaceCollision

Raises when attempting to assign a variable to a name that is already in use.

exception NatSpecSyntaxException

Raises when a contract contains an invalid NatSpec docstring.

vyper.exceptions.SyntaxException: line 14:5 No description given for tag '@param'
     13     @dev the feet are sticky like rice
---> 14     @param
     15     @return always True
exception NonPayableViolation

Raises when attempting to access msg.value from within a private function.

def _foo():
    bar: uint256 = msg.value
exception OverflowException

Raises when a numeric value is out of bounds for the given type.

exception StructureException

Raises on syntax that is parsable, but invalid in some way.

vyper.exceptions.StructureException: line 181:0 Invalid top-level statement
---> 181 '''
exception SyntaxException

Raises on invalid syntax that cannot be parsed.

vyper.exceptions.SyntaxException: line 4:20 invalid syntax
        3 struct Bid:
---> 4   blindedBid bytes32
        5   deposit: wei_value
exception TypeMismatch

Raises when attempting to perform an action between multiple objects of incompatible types.

vyper.exceptions.TypeMismatchException: line 4:4 Invalid type, expected: bytes32
     3     a: uint256 = 1
---> 4     b: bytes32 = a

b has been set as type bytes32 but the assignment is to a which is uint256.

exception UndeclaredDefinition

Raises when attempting to access an object that has not been declared.

exception VariableDeclarationException

Raises on an invalid variable declaration.

vyper.exceptions.VariableDeclarationException: line 79:17 Persistent variable undeclared: highstBid
     78     # If bid is less than highest bid, bid fails
---> 79     if (value <= self.highstBid):
     80         return False
exception VersionException

Raises when a contract version string is malformed or incompatible with the current compiler version.

exception ZeroDivisionException

Raises when a divide by zero or modulo zero situation arises.


exception CompilerPanic
$ vyper v.vy
Error compiling: v.vy
vyper.exceptions.CompilerPanic: Number of times repeated
must be a constant nonzero positive integer: 0 Please create an issue.

A compiler panic error indicates that there is a problem internally to the compiler and an issue should be reported right away on the Vyper Github page. Open an issue if you are experiencing this error. Please Open an Issue