Release: 2.0.49 | Release Date: April 3, 2026

# SQLAlchemy 2.0 Documentation

# Core Exceptions

Exceptions used with SQLAlchemy.

The base exception class is `SQLAlchemyError`. Exceptions which are raised as a result of DBAPI exceptions are all subclasses of `DBAPIError`.

exception sqlalchemy.exc.AmbiguousForeignKeysError

  inherits from `sqlalchemy.exc.ArgumentError`

  Raised when more than one foreign key matching can be located between two selectables during a join.

exception sqlalchemy.exc.ArgumentError

  inherits from `sqlalchemy.exc.SQLAlchemyError`

  Raised when an invalid or conflicting function argument is supplied.

  This error generally corresponds to construction time state errors.

exception sqlalchemy.exc.AwaitRequired

  inherits from `sqlalchemy.exc.InvalidRequestError`

  Error raised by the async greenlet spawn if no async operation was awaited when it required one.

exception sqlalchemy.exc.Base20DeprecationWarning

  inherits from `sqlalchemy.exc.SADeprecationWarning`

  Issued for usage of APIs specifically deprecated or legacy in SQLAlchemy 2.0.

  See also

  The <some function> in SQLAlchemy 2.0 will no longer <something>.

  SQLAlchemy 2.0 Deprecations Mode

  attribute `sqlalchemy.exc.Base20DeprecationWarning.`deprecated_since: str | None = '1.4'

    Indicates the version that started raising this deprecation warning

exception sqlalchemy.exc.CircularDependencyError

  inherits from `sqlalchemy.exc.SQLAlchemyError`

  Raised by topological sorts when a circular dependency is detected.

  There are two scenarios where this error occurs:

  - In a Session flush operation, if two objects are mutually dependent on each other, they can not be inserted or deleted via INSERT or DELETE statements alone; an UPDATE will be needed to post-associate or pre-deassociate one of the foreign key constrained values. The `post_update` flag described at Rows that point to themselves / Mutually Dependent Rows can resolve this cycle.

  - In a `MetaData.sorted_tables` operation, two `ForeignKey` or `ForeignKeyConstraint` objects mutually refer to each other. Apply the `use_alter=True` flag to one or both, see Creating/Dropping Foreign Key Constraints via ALTER.

  method `sqlalchemy.exc.CircularDependencyError.`__init__(message: str, cycles: Any, edges: Any, msg: str | None = None, code: str | None = None)

exception sqlalchemy.exc.CompileError

  inherits from `sqlalchemy.exc.SQLAlchemyError`

  Raised when an error occurs during SQL compilation

exception sqlalchemy.exc.ConstraintColumnNotFoundError

  inherits from `sqlalchemy.exc.ArgumentError`

  raised when a constraint refers to a string column name that is not present in the table being constrained.

  Added in version 2.0.

exception sqlalchemy.exc.DBAPIError

  inherits from `sqlalchemy.exc.StatementError`

  Raised when the execution of a database operation fails.

  Wraps exceptions raised by the DB-API underlying the database operation. Driver-specific implementations of the standard DB-API exception types are wrapped by matching sub-types of SQLAlchemy’s `DBAPIError` when possible. DB-API’s `Error` type maps to `DBAPIError` in SQLAlchemy, otherwise the names are identical. Note that there is no guarantee that different DB-API implementations will raise the same exception type for any given error condition.

  `DBAPIError` features `StatementError.statement` and `StatementError.params` attributes which supply context regarding the specifics of the statement which had an issue, for the typical case when the error was raised within the context of emitting a SQL statement.

  The wrapped exception object is available in the `StatementError.orig` attribute. Its type and properties are DB-API implementation specific.

  method `sqlalchemy.exc.DBAPIError.`__init__(statement: str | None, params: _AnyExecuteParams | None, orig: BaseException, hide_parameters: bool = False, connection_invalidated: bool = False, code: str | None = None, ismulti: bool | None = None)

exception sqlalchemy.exc.DataError

  inherits from `sqlalchemy.exc.DatabaseError`

  Wraps a DB-API DataError.

exception sqlalchemy.exc.DatabaseError

  inherits from `sqlalchemy.exc.DBAPIError`

  Wraps a DB-API DatabaseError.

exception sqlalchemy.exc.DisconnectionError

  inherits from `sqlalchemy.exc.SQLAlchemyError`

  A disconnect is detected on a raw DB-API connection.

  This error is raised and consumed internally by a connection pool. It can be raised by the `PoolEvents.checkout()` event so that the host pool forces a retry; the exception will be caught three times in a row before the pool gives up and raises `InvalidRequestError` regarding the connection attempt.

Object Name | Description
--- | ---
DontWrapMixin | A mixin class which, when applied to a user-defined Exception class, will not be wrapped inside of `StatementError` if the error is emitted within the process of executing a statement.
HasDescriptionCode | helper which adds ‘code’ as an attribute and ‘_code_str’ as a method

class sqlalchemy.exc.DontWrapMixin

  A mixin class which, when applied to a user-defined Exception class, will not be wrapped inside of `StatementError` if the error is emitted within the process of executing a statement.

  E.g.:

      from sqlalchemy.exc import DontWrapMixin

      class MyCustomException(Exception, DontWrapMixin):
          pass

      class MySpecialType(TypeDecorator):
          impl = String

          def process_bind_param(self, value, dialect):
              if value == "invalid":
                  raise MyCustomException("invalid!")

exception sqlalchemy.exc.DuplicateColumnError

  inherits from `sqlalchemy.exc.ArgumentError`

  a Column is being added to a Table that would replace another Column, without appropriate parameters to allow this in place.

  Added in version 2.0.0b4.

class sqlalchemy.exc.HasDescriptionCode

  helper which adds ‘code’ as an attribute and ‘_code_str’ as a method

exception sqlalchemy.exc.IdentifierError

  inherits from `sqlalchemy.exc.SQLAlchemyError`

  Raised when a schema name is beyond the max character limit

exception sqlalchemy.exc.IllegalStateChangeError

  inherits from `sqlalchemy.exc.InvalidRequestError`

  An object that tracks state encountered an illegal state change of some kind.

  Added in version 2.0.

exception sqlalchemy.exc.IntegrityError

  inherits from `sqlalchemy.exc.DatabaseError`

  Wraps a DB-API IntegrityError.

exception sqlalchemy.exc.InterfaceError

  inherits from `sqlalchemy.exc.DBAPIError`

  Wraps a DB-API InterfaceError.

exception sqlalchemy.exc.InternalError

  inherits from `sqlalchemy.exc.DatabaseError`

  Wraps a DB-API InternalError.

exception sqlalchemy.exc.InvalidRequestError

  inherits from `sqlalchemy.exc.SQLAlchemyError`

  SQLAlchemy was asked to do something it can’t do.

  This error generally corresponds to runtime state errors.

exception sqlalchemy.exc.InvalidatePoolError

  inherits from `sqlalchemy.exc.DisconnectionError`

  Raised when the connection pool should invalidate all stale connections.

  A subclass of `DisconnectionError` that indicates that the disconnect situation encountered on the connection probably means the entire pool should be invalidated, as the database has been restarted.

  This exception will be handled otherwise the same way as `DisconnectionError`, allowing three attempts to reconnect before giving up.

  Added in version 1.2.

exception sqlalchemy.exc.LegacyAPIWarning

  inherits from `sqlalchemy.exc.Base20DeprecationWarning`

  indicates an API that is in ‘legacy’ status, a long term deprecation.

exception sqlalchemy.exc.MissingGreenlet

  inherits from `sqlalchemy.exc.InvalidRequestError`

  Error raised by the async greenlet await_ if called while not inside the greenlet spawn context.

exception sqlalchemy.exc.MovedIn20Warning

  inherits from `sqlalchemy.exc.Base20DeprecationWarning`

  Subtype of RemovedIn20Warning to indicate an API that moved only.

exception sqlalchemy.exc.MultipleResultsFound

  inherits from `sqlalchemy.exc.InvalidRequestError`

  A single database result was required but more than one were found.

  Changed in version 1.4: This exception is now part of the `sqlalchemy.exc` module in Core, moved from the ORM. The symbol remains importable from `sqlalchemy.orm.exc`.

exception sqlalchemy.exc.NoForeignKeysError

  inherits from `sqlalchemy.exc.ArgumentError`

  Raised when no foreign keys can be located between two selectables during a join.

exception sqlalchemy.exc.NoInspectionAvailable

  inherits from `sqlalchemy.exc.InvalidRequestError`

  A subject passed to `sqlalchemy.inspection.inspect()` produced no context for inspection.

exception sqlalchemy.exc.NoReferenceError

  inherits from `sqlalchemy.exc.InvalidRequestError`

  Raised by `ForeignKey` to indicate a reference cannot be resolved.

exception sqlalchemy.exc.NoReferencedColumnError

  inherits from `sqlalchemy.exc.NoReferenceError`

  Raised by `ForeignKey` when the referred `Column` cannot be located.

  method `sqlalchemy.exc.NoReferencedColumnError.`__init__(message: str, tname: str, cname: str)

exception sqlalchemy.exc.NoReferencedTableError

  inherits from `sqlalchemy.exc.NoReferenceError`

  Raised by `ForeignKey` when the referred `Table` cannot be located.

  method `sqlalchemy.exc.NoReferencedTableError.`__init__(message: str, tname: str)

exception sqlalchemy.exc.NoResultFound

  inherits from `sqlalchemy.exc.InvalidRequestError`

  A database result was required but none was found.

  Changed in version 1.4: This exception is now part of the `sqlalchemy.exc` module in Core, moved from the ORM. The symbol remains importable from `sqlalchemy.orm.exc`.

exception sqlalchemy.exc.NoSuchColumnError

  inherits from `sqlalchemy.exc.InvalidRequestError`, `builtins.KeyError`

  A nonexistent column is requested from a `Row`.

exception sqlalchemy.exc.NoSuchModuleError

  inherits from `sqlalchemy.exc.ArgumentError`

  Raised when a dynamically-loaded module (usually a database dialect) of a particular name cannot be located.

exception sqlalchemy.exc.NoSuchTableError

  inherits from `sqlalchemy.exc.InvalidRequestError`

  Table does not exist or is not visible to a connection.

exception sqlalchemy.exc.NotSupportedError

  inherits from `sqlalchemy.exc.DatabaseError`

  Wraps a DB-API NotSupportedError.

exception sqlalchemy.exc.ObjectNotExecutableError

  inherits from `sqlalchemy.exc.ArgumentError`

  Raised when an object is passed to .execute() that can’t be executed as SQL.

  method `sqlalchemy.exc.ObjectNotExecutableError.`__init__(target: Any)

exception sqlalchemy.exc.OperationalError

  inherits from `sqlalchemy.exc.DatabaseError`

  Wraps a DB-API OperationalError.

exception sqlalchemy.exc.PendingRollbackError

  inherits from `sqlalchemy.exc.InvalidRequestError`

  A transaction has failed and needs to be rolled back before continuing.

  Added in version 1.4.

exception sqlalchemy.exc.ProgrammingError

  inherits from `sqlalchemy.exc.DatabaseError`

  Wraps a DB-API ProgrammingError.

exception sqlalchemy.exc.ResourceClosedError

  inherits from `sqlalchemy.exc.InvalidRequestError`

  An operation was requested from a connection, cursor, or other object that’s in a closed state.

exception sqlalchemy.exc.SADeprecationWarning

  inherits from `sqlalchemy.exc.HasDescriptionCode`, `builtins.DeprecationWarning`

  Issued for usage of deprecated APIs.

  attribute `sqlalchemy.exc.SADeprecationWarning.`deprecated_since: str | None = None

    Indicates the version that started raising this deprecation warning

exception sqlalchemy.exc.SAPendingDeprecationWarning

  inherits from `builtins.PendingDeprecationWarning`

  A similar warning as `SADeprecationWarning`, this warning is not used in modern versions of SQLAlchemy.

  attribute `sqlalchemy.exc.SAPendingDeprecationWarning.`deprecated_since: str | None = None

    Indicates the version that started raising this deprecation warning

exception sqlalchemy.exc.SATestSuiteWarning

  inherits from `builtins.Warning`

  warning for a condition detected during tests that is non-fatal

  Currently outside of SAWarning so that we can work around tools like Alembic doing the wrong thing with warnings.

exception sqlalchemy.exc.SAWarning

  inherits from `sqlalchemy.exc.HasDescriptionCode`, `builtins.RuntimeWarning`

  Issued at runtime.

exception sqlalchemy.exc.SQLAlchemyError

  inherits from `sqlalchemy.exc.HasDescriptionCode`, `builtins.Exception`

  Generic error class.

exception sqlalchemy.exc.StatementError

  inherits from `sqlalchemy.exc.SQLAlchemyError`

  An error occurred during execution of a SQL statement.

  `StatementError` wraps the exception raised during execution, and features `statement` and `params` attributes which supply context regarding the specifics of the statement which had an issue.

  The wrapped exception object is available in the `orig` attribute.

  method `sqlalchemy.exc.StatementError.`__init__(message: str, statement: str | None, params: _AnyExecuteParams | None, orig: BaseException | None, hide_parameters: bool = False, code: str | None = None, ismulti: bool | None = None)
  attribute `sqlalchemy.exc.StatementError.`ismulti: bool | None = None

    multi parameter passed to repr_params(). None is meaningful.

  attribute `sqlalchemy.exc.StatementError.`orig: BaseException | None = None

    The original exception that was thrown.

  attribute `sqlalchemy.exc.StatementError.`params: _AnyExecuteParams | None = None

    The parameter list being used when this exception occurred.

  attribute `sqlalchemy.exc.StatementError.`statement: str | None = None

    The string SQL statement being invoked when this exception occurred.

exception sqlalchemy.exc.TimeoutError

  inherits from `sqlalchemy.exc.SQLAlchemyError`

  Raised when a connection pool times out on getting a connection.

exception sqlalchemy.exc.UnboundExecutionError

  inherits from `sqlalchemy.exc.InvalidRequestError`

  SQL was attempted without a database connection to execute it on.

exception sqlalchemy.exc.UnreflectableTableError

  inherits from `sqlalchemy.exc.InvalidRequestError`

  Table exists but can’t be reflected for some reason.

  Added in version 1.2.

exception sqlalchemy.exc.UnsupportedCompilationError

  inherits from `sqlalchemy.exc.CompileError`

  Raised when an operation is not supported by the given compiler.

  See also

  How do I render SQL expressions as strings, possibly with bound parameters inlined?

  Compiler StrSQLCompiler can’t render element of type <element type>

  method `sqlalchemy.exc.UnsupportedCompilationError.`__init__(compiler: Compiled | TypeCompiler, element_type: Type[ClauseElement], message: str | None = None)