Release: 2.0.41 | Release Date: May 14, 2025

# 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

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

  Class signature

  class `sqlalchemy.exc.AmbiguousForeignKeysError` (`sqlalchemy.exc.ArgumentError`)

exception sqlalchemy.exc.ArgumentError

  Raised when an invalid or conflicting function argument is supplied.

  This error generally corresponds to construction time state errors.

  Class signature

  class `sqlalchemy.exc.ArgumentError` (`sqlalchemy.exc.SQLAlchemyError`)

exception sqlalchemy.exc.AwaitRequired

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

  Class signature

  class `sqlalchemy.exc.AwaitRequired` (`sqlalchemy.exc.InvalidRequestError`)

exception sqlalchemy.exc.Base20DeprecationWarning

  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

  Class signature

  class `sqlalchemy.exc.Base20DeprecationWarning` (`sqlalchemy.exc.SADeprecationWarning`)

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

    Indicates the version that started raising this deprecation warning

exception sqlalchemy.exc.CircularDependencyError

  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.

  Class signature

  class `sqlalchemy.exc.CircularDependencyError` (`sqlalchemy.exc.SQLAlchemyError`)

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

exception sqlalchemy.exc.CompileError

  Raised when an error occurs during SQL compilation

  Class signature

  class `sqlalchemy.exc.CompileError` (`sqlalchemy.exc.SQLAlchemyError`)

exception sqlalchemy.exc.ConstraintColumnNotFoundError

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

  New in version 2.0.

  Class signature

  class `sqlalchemy.exc.ConstraintColumnNotFoundError` (`sqlalchemy.exc.ArgumentError`)

exception sqlalchemy.exc.DBAPIError

  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.

  Class signature

  class `sqlalchemy.exc.DBAPIError` (`sqlalchemy.exc.StatementError`)

  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

  Wraps a DB-API DataError.

  Class signature

  class `sqlalchemy.exc.DataError` (`sqlalchemy.exc.DatabaseError`)

exception sqlalchemy.exc.DatabaseError

  Wraps a DB-API DatabaseError.

  Class signature

  class `sqlalchemy.exc.DatabaseError` (`sqlalchemy.exc.DBAPIError`)

exception sqlalchemy.exc.DisconnectionError

  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.

  Class signature

  class `sqlalchemy.exc.DisconnectionError` (`sqlalchemy.exc.SQLAlchemyError`)

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

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

  New in version 2.0.0b4.

  Class signature

  class `sqlalchemy.exc.DuplicateColumnError` (`sqlalchemy.exc.ArgumentError`)

class sqlalchemy.exc.HasDescriptionCode

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

exception sqlalchemy.exc.IdentifierError

  Raised when a schema name is beyond the max character limit

  Class signature

  class `sqlalchemy.exc.IdentifierError` (`sqlalchemy.exc.SQLAlchemyError`)

exception sqlalchemy.exc.IllegalStateChangeError

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

  New in version 2.0.

  Class signature

  class `sqlalchemy.exc.IllegalStateChangeError` (`sqlalchemy.exc.InvalidRequestError`)

exception sqlalchemy.exc.IntegrityError

  Wraps a DB-API IntegrityError.

  Class signature

  class `sqlalchemy.exc.IntegrityError` (`sqlalchemy.exc.DatabaseError`)

exception sqlalchemy.exc.InterfaceError

  Wraps a DB-API InterfaceError.

  Class signature

  class `sqlalchemy.exc.InterfaceError` (`sqlalchemy.exc.DBAPIError`)

exception sqlalchemy.exc.InternalError

  Wraps a DB-API InternalError.

  Class signature

  class `sqlalchemy.exc.InternalError` (`sqlalchemy.exc.DatabaseError`)

exception sqlalchemy.exc.InvalidRequestError

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

  This error generally corresponds to runtime state errors.

  Class signature

  class `sqlalchemy.exc.InvalidRequestError` (`sqlalchemy.exc.SQLAlchemyError`)

exception sqlalchemy.exc.InvalidatePoolError

  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.

  New in version 1.2.

  Class signature

  class `sqlalchemy.exc.InvalidatePoolError` (`sqlalchemy.exc.DisconnectionError`)

exception sqlalchemy.exc.LegacyAPIWarning

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

  Class signature

  class `sqlalchemy.exc.LegacyAPIWarning` (`sqlalchemy.exc.Base20DeprecationWarning`)

exception sqlalchemy.exc.MissingGreenlet

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

  Class signature

  class `sqlalchemy.exc.MissingGreenlet` (`sqlalchemy.exc.InvalidRequestError`)

exception sqlalchemy.exc.MovedIn20Warning

  Subtype of RemovedIn20Warning to indicate an API that moved only.

  Class signature

  class `sqlalchemy.exc.MovedIn20Warning` (`sqlalchemy.exc.Base20DeprecationWarning`)

exception sqlalchemy.exc.MultipleResultsFound

  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`.

  Class signature

  class `sqlalchemy.exc.MultipleResultsFound` (`sqlalchemy.exc.InvalidRequestError`)

exception sqlalchemy.exc.NoForeignKeysError

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

  Class signature

  class `sqlalchemy.exc.NoForeignKeysError` (`sqlalchemy.exc.ArgumentError`)

exception sqlalchemy.exc.NoInspectionAvailable

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

  Class signature

  class `sqlalchemy.exc.NoInspectionAvailable` (`sqlalchemy.exc.InvalidRequestError`)

exception sqlalchemy.exc.NoReferenceError

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

  Class signature

  class `sqlalchemy.exc.NoReferenceError` (`sqlalchemy.exc.InvalidRequestError`)

exception sqlalchemy.exc.NoReferencedColumnError

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

  Class signature

  class `sqlalchemy.exc.NoReferencedColumnError` (`sqlalchemy.exc.NoReferenceError`)

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

exception sqlalchemy.exc.NoReferencedTableError

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

  Class signature

  class `sqlalchemy.exc.NoReferencedTableError` (`sqlalchemy.exc.NoReferenceError`)

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

exception sqlalchemy.exc.NoResultFound

  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`.

  Class signature

  class `sqlalchemy.exc.NoResultFound` (`sqlalchemy.exc.InvalidRequestError`)

exception sqlalchemy.exc.NoSuchColumnError

  A nonexistent column is requested from a `Row`.

  Class signature

  class `sqlalchemy.exc.NoSuchColumnError` (`sqlalchemy.exc.InvalidRequestError`, `builtins.KeyError`)

exception sqlalchemy.exc.NoSuchModuleError

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

  Class signature

  class `sqlalchemy.exc.NoSuchModuleError` (`sqlalchemy.exc.ArgumentError`)

exception sqlalchemy.exc.NoSuchTableError

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

  Class signature

  class `sqlalchemy.exc.NoSuchTableError` (`sqlalchemy.exc.InvalidRequestError`)

exception sqlalchemy.exc.NotSupportedError

  Wraps a DB-API NotSupportedError.

  Class signature

  class `sqlalchemy.exc.NotSupportedError` (`sqlalchemy.exc.DatabaseError`)

exception sqlalchemy.exc.ObjectNotExecutableError

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

  Class signature

  class `sqlalchemy.exc.ObjectNotExecutableError` (`sqlalchemy.exc.ArgumentError`)

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

exception sqlalchemy.exc.OperationalError

  Wraps a DB-API OperationalError.

  Class signature

  class `sqlalchemy.exc.OperationalError` (`sqlalchemy.exc.DatabaseError`)

exception sqlalchemy.exc.PendingRollbackError

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

  New in version 1.4.

  Class signature

  class `sqlalchemy.exc.PendingRollbackError` (`sqlalchemy.exc.InvalidRequestError`)

exception sqlalchemy.exc.ProgrammingError

  Wraps a DB-API ProgrammingError.

  Class signature

  class `sqlalchemy.exc.ProgrammingError` (`sqlalchemy.exc.DatabaseError`)

exception sqlalchemy.exc.ResourceClosedError

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

  Class signature

  class `sqlalchemy.exc.ResourceClosedError` (`sqlalchemy.exc.InvalidRequestError`)

exception sqlalchemy.exc.SADeprecationWarning

  Issued for usage of deprecated APIs.

  Class signature

  class `sqlalchemy.exc.SADeprecationWarning` (`sqlalchemy.exc.HasDescriptionCode`, `builtins.DeprecationWarning`)

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

    Indicates the version that started raising this deprecation warning

exception sqlalchemy.exc.SAPendingDeprecationWarning

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

  Class signature

  class `sqlalchemy.exc.SAPendingDeprecationWarning` (`builtins.PendingDeprecationWarning`)

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

    Indicates the version that started raising this deprecation warning

exception sqlalchemy.exc.SATestSuiteWarning

  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.

  Class signature

  class `sqlalchemy.exc.SATestSuiteWarning` (`builtins.Warning`)

exception sqlalchemy.exc.SAWarning

  Issued at runtime.

  Class signature

  class `sqlalchemy.exc.SAWarning` (`sqlalchemy.exc.HasDescriptionCode`, `builtins.RuntimeWarning`)

exception sqlalchemy.exc.SQLAlchemyError

  Generic error class.

  Class signature

  class `sqlalchemy.exc.SQLAlchemyError` (`sqlalchemy.exc.HasDescriptionCode`, `builtins.Exception`)

exception sqlalchemy.exc.StatementError

  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.

  Class signature

  class `sqlalchemy.exc.StatementError` (`sqlalchemy.exc.SQLAlchemyError`)

  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

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

  Class signature

  class `sqlalchemy.exc.TimeoutError` (`sqlalchemy.exc.SQLAlchemyError`)

exception sqlalchemy.exc.UnboundExecutionError

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

  Class signature

  class `sqlalchemy.exc.UnboundExecutionError` (`sqlalchemy.exc.InvalidRequestError`)

exception sqlalchemy.exc.UnreflectableTableError

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

  New in version 1.2.

  Class signature

  class `sqlalchemy.exc.UnreflectableTableError` (`sqlalchemy.exc.InvalidRequestError`)

exception sqlalchemy.exc.UnsupportedCompilationError

  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>

  Class signature

  class `sqlalchemy.exc.UnsupportedCompilationError` (`sqlalchemy.exc.CompileError`)

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