Built-in Exceptions

In Python, all exceptions must be instances of a class that derives from BaseException.In atrystatement with anexcept clause that mentions a particular class, that clause also handles any exception classes derived from that class (but not exception classes from whichitis derived). Two exception classes that are not related via subclassing are never equivalent, even if they have the same name.

The built-in exceptions listed in this chapter can be generated by the interpreter or built-in functions. Except where mentioned, they have an “associated value” indicating the detailed cause of the error. This may be a string or a tuple of several items of information (e.g., an error code and a string explaining the code). The associated value is usually passed as arguments to the exception class’s constructor.

User code can raise built-in exceptions. This can be used to test an exception handler or to report an error condition “just like” the situation in which the interpreter raises the same exception; but beware that there is nothing to prevent user code from raising an inappropriate error.

The built-in exception classes can be subclassed to define new exceptions; programmers are encouraged to derive new exceptions from theException class or one of its subclasses, and not fromBaseException.More information on defining exceptions is available in the Python Tutorial under User-defined Exceptions.

Exception context

Three attributes on exception objects provide information about the context in which the exception was raised:

BaseException.__context__

BaseException.__cause__

BaseException.__suppress_context__

When raising a new exception while another exception is already being handled, the new exception’s __context__attribute is automatically set to the handled exception. An exception may be handled when anexceptor finallyclause, or awithstatement, is used.

This implicit exception context can be supplemented with an explicit cause by usingfromwith raise:

raisenew_excfromoriginal_exc

The expression followingfrommust be an exception orNone.It will be set as__cause__on the raised exception. Setting __cause__also implicitly sets the__suppress_context__ attribute toTrue,so that usingraisenew_excfromNone effectively replaces the old exception with the new one for display purposes (e.g. convertingKeyErrortoAttributeError), while leaving the old exception available in__context__for introspection when debugging.

The default traceback display code shows these chained exceptions in addition to the traceback for the exception itself. An explicitly chained exception in__cause__is always shown when present. An implicitly chained exception in__context__is shown only if__cause__ isNoneand__suppress_context__is false.

In either case, the exception itself is always shown after any chained exceptions so that the final line of the traceback always shows the last exception that was raised.

Inheriting from built-in exceptions

User code can create subclasses that inherit from an exception type. It’s recommended to only subclass one exception type at a time to avoid any possible conflicts between how the bases handle theargs attribute, as well as due to possible memory layout incompatibilities.

CPython implementation detail:Most built-in exceptions are implemented in C for efficiency, see: Objects/exceptions.c.Some have custom memory layouts which makes it impossible to create a subclass that inherits from multiple exception types. The memory layout of a type is an implementation detail and might change between Python versions, leading to new conflicts in the future. Therefore, it’s recommended to avoid subclassing multiple exception types altogether.

Base classes

The following exceptions are used mostly as base classes for other exceptions.

exceptionBaseException

The base class for all built-in exceptions. It is not meant to be directly inherited by user-defined classes (for that, useException). If str()is called on an instance of this class, the representation of the argument(s) to the instance are returned, or the empty string when there were no arguments.

args

The tuple of arguments given to the exception constructor. Some built-in exceptions (likeOSError) expect a certain number of arguments and assign a special meaning to the elements of this tuple, while others are usually called only with a single string giving an error message.

with_traceback(tb)

This method setstbas the new traceback for the exception and returns the exception object. It was more commonly used before the exception chaining features ofPEP 3134became available. The following example shows how we can convert an instance ofSomeExceptioninto an instance ofOtherExceptionwhile preserving the traceback. Once raised, the current frame is pushed onto the traceback of the OtherException,as would have happened to the traceback of the originalSomeExceptionhad we allowed it to propagate to the caller.

try:
...
exceptSomeException:
tb=sys.exception().__traceback__
raiseOtherException(...).with_traceback(tb)

__traceback__

A writable field that holds the traceback objectassociated with this exception. See also:The raise statement.

add_note(note)

Add the stringnoteto the exception’s notes which appear in the standard traceback after the exception string. ATypeErroris raised ifnote is not a string.

Added in version 3.11.

__notes__

A list of the notes of this exception, which were added withadd_note(). This attribute is created whenadd_note()is called.

Added in version 3.11.

exceptionException

All built-in, non-system-exiting exceptions are derived from this class. All user-defined exceptions should also be derived from this class.

exceptionArithmeticError

The base class for those built-in exceptions that are raised for various arithmetic errors:OverflowError,ZeroDivisionError, FloatingPointError.

exceptionBufferError

Raised when abufferrelated operation cannot be performed.

exceptionLookupError

The base class for the exceptions that are raised when a key or index used on a mapping or sequence is invalid:IndexError,KeyError.This can be raised directly bycodecs.lookup().

Concrete exceptions

The following exceptions are the exceptions that are usually raised.

exceptionAssertionError

Raised when anassertstatement fails.

exceptionAttributeError

Raised when an attribute reference (seeAttribute references) or assignment fails. (When an object does not support attribute references or attribute assignments at all,TypeErroris raised.)

Thenameandobjattributes can be set using keyword-only arguments to the constructor. When set they represent the name of the attribute that was attempted to be accessed and the object that was accessed for said attribute, respectively.

Changed in version 3.10:Added thenameandobjattributes.

exceptionEOFError

Raised when theinput()function hits an end-of-file condition (EOF) without reading any data. (N.B.: theio.IOBase.read()and io.IOBase.readline()methods return an empty string when they hit EOF.)

exceptionFloatingPointError

Not currently used.

exceptionGeneratorExit

Raised when ageneratororcoroutineis closed; seegenerator.close()andcoroutine.close().It directly inherits fromBaseExceptioninstead ofExceptionsince it is technically not an error.

exceptionImportError

Raised when theimportstatement has troubles trying to load a module. Also raised when the “from list” infrom...import has a name that cannot be found.

The optionalnameandpathkeyword-only arguments set the corresponding attributes:

name

The name of the module that was attempted to be imported.

path

The path to any file which triggered the exception.

Changed in version 3.3:Added thenameandpathattributes.

exceptionModuleNotFoundError

A subclass ofImportErrorwhich is raised byimport when a module could not be located. It is also raised whenNone is found insys.modules.

Added in version 3.6.

exceptionIndexError

Raised when a sequence subscript is out of range. (Slice indices are silently truncated to fall in the allowed range; if an index is not an integer,TypeErroris raised.)

exceptionKeyError

Raised when a mapping (dictionary) key is not found in the set of existing keys.

exceptionKeyboardInterrupt

Raised when the user hits the interrupt key (normallyControl-Cor Delete). During execution, a check for interrupts is made regularly. The exception inherits fromBaseExceptionso as to not be accidentally caught by code that catchesExceptionand thus prevent the interpreter from exiting.

Note

Catching aKeyboardInterruptrequires special consideration. Because it can be raised at unpredictable points, it may, in some circumstances, leave the running program in an inconsistent state. It is generally best to allowKeyboardInterruptto end the program as quickly as possible or avoid raising it entirely. (See Note on Signal Handlers and Exceptions.)

exceptionMemoryError

Raised when an operation runs out of memory but the situation may still be rescued (by deleting some objects). The associated value is a string indicating what kind of (internal) operation ran out of memory. Note that because of the underlying memory management architecture (C’smalloc()function), the interpreter may not always be able to completely recover from this situation; it nevertheless raises an exception so that a stack traceback can be printed, in case a run-away program was the cause.

exceptionNameError

Raised when a local or global name is not found. This applies only to unqualified names. The associated value is an error message that includes the name that could not be found.

Thenameattribute can be set using a keyword-only argument to the constructor. When set it represent the name of the variable that was attempted to be accessed.

Changed in version 3.10:Added thenameattribute.

exceptionNotImplementedError

This exception is derived fromRuntimeError.In user defined base classes, abstract methods should raise this exception when they require derived classes to override the method, or while the class is being developed to indicate that the real implementation still needs to be added.

Note

It should not be used to indicate that an operator or method is not meant to be supported at all – in that case either leave the operator / method undefined or, if a subclass, set it toNone.

Note

NotImplementedErrorandNotImplementedare not interchangeable, even though they have similar names and purposes. See NotImplementedfor details on when to use it.

exceptionOSError([arg])

exceptionOSError(errno,strerror[,filename[,winerror[,filename2]]])

This exception is raised when a system function returns a system-related error, including I/O failures such as “file not found” or “disk full” (not for illegal argument types or other incidental errors).

The second form of the constructor sets the corresponding attributes, described below. The attributes default toNoneif not specified. For backwards compatibility, if three arguments are passed, theargsattribute contains only a 2-tuple of the first two constructor arguments.

The constructor often actually returns a subclass ofOSError,as described inOS exceptionsbelow. The particular subclass depends on the finalerrnovalue. This behaviour only occurs when constructingOSErrordirectly or via an alias, and is not inherited when subclassing.

errno

A numeric error code from the C variableerrno.

winerror

Under Windows, this gives you the native Windows error code. Theerrnoattribute is then an approximate translation, in POSIX terms, of that native error code.

Under Windows, if thewinerrorconstructor argument is an integer, theerrnoattribute is determined from the Windows error code, and theerrnoargument is ignored. On other platforms, the winerrorargument is ignored, and thewinerrorattribute does not exist.

strerror

The corresponding error message, as provided by the operating system. It is formatted by the C functionsperror()under POSIX, andFormatMessage() under Windows.

filename

filename2

For exceptions that involve a file system path (such asopen()or os.unlink()),filenameis the file name passed to the function. For functions that involve two file system paths (such as os.rename()),filename2corresponds to the second file name passed to the function.

Changed in version 3.3:EnvironmentError,IOError,WindowsError, socket.error,select.errorand mmap.errorhave been merged intoOSError,and the constructor may return a subclass.

Changed in version 3.4:Thefilenameattribute is now the original file name passed to the function, instead of the name encoded to or decoded from the filesystem encoding and error handler.Also, thefilename2 constructor argument and attribute was added.

exceptionOverflowError

Raised when the result of an arithmetic operation is too large to be represented. This cannot occur for integers (which would rather raise MemoryErrorthan give up). However, for historical reasons, OverflowError is sometimes raised for integers that are outside a required range. Because of the lack of standardization of floating-point exception handling in C, most floating-point operations are not checked.

exceptionRecursionError

This exception is derived fromRuntimeError.It is raised when the interpreter detects that the maximum recursion depth (see sys.getrecursionlimit()) is exceeded.

Added in version 3.5:Previously, a plainRuntimeErrorwas raised.

exceptionReferenceError

This exception is raised when a weak reference proxy, created by the weakref.proxy()function, is used to access an attribute of the referent after it has been garbage collected. For more information on weak references, see theweakrefmodule.

exceptionRuntimeError

Raised when an error is detected that doesn’t fall in any of the other categories. The associated value is a string indicating what precisely went wrong.

exceptionStopIteration

Raised by built-in functionnext()and aniterator's __next__()method to signal that there are no further items produced by the iterator.

value

The exception object has a single attributevalue,which is given as an argument when constructing the exception, and defaults toNone.

When ageneratororcoroutinefunction returns, a newStopIterationinstance is raised, and the value returned by the function is used as the valueparameter to the constructor of the exception.

If a generator code directly or indirectly raisesStopIteration, it is converted into aRuntimeError(retaining the StopIterationas the new exception’s cause).

Changed in version 3.3:Addedvalueattribute and the ability for generator functions to use it to return a value.

Changed in version 3.5:Introduced the RuntimeError transformation via from__future__importgenerator_stop,seePEP 479.

Changed in version 3.7:EnablePEP 479for all code by default: aStopIteration error raised in a generator is transformed into aRuntimeError.

exceptionStopAsyncIteration

Must be raised by__anext__()method of an asynchronous iteratorobject to stop the iteration.

Added in version 3.5.

exceptionSyntaxError(message,details)

Raised when the parser encounters a syntax error. This may occur in an importstatement, in a call to the built-in functions compile(),exec(), oreval(),or when reading the initial script or standard input (also interactively).

Thestr()of the exception instance returns only the error message. Details is a tuple whose members are also available as separate attributes.

filename

The name of the file the syntax error occurred in.

lineno

Which line number in the file the error occurred in. This is 1-indexed: the first line in the file has alinenoof 1.

offset

The column in the line where the error occurred. This is 1-indexed: the first character in the line has anoffsetof 1.

text

The source code text involved in the error.

end_lineno

Which line number in the file the error occurred ends in. This is 1-indexed: the first line in the file has alinenoof 1.

end_offset

The column in the end line where the error occurred finishes. This is 1-indexed: the first character in the line has anoffsetof 1.

For errors in f-string fields, the message is prefixed by “f-string:” and the offsets are offsets in a text constructed from the replacement expression. For example, compiling f’Bad {a b} field’ results in this args attribute: (‘f-string:…’, (‘’, 1, 2, ‘(a b)n’, 1, 5)).

Changed in version 3.10:Added theend_linenoandend_offsetattributes.

exceptionIndentationError

Base class for syntax errors related to incorrect indentation. This is a subclass ofSyntaxError.

exceptionTabError

Raised when indentation contains an inconsistent use of tabs and spaces. This is a subclass ofIndentationError.

exceptionSystemError

Raised when the interpreter finds an internal error, but the situation does not look so serious to cause it to abandon all hope. The associated value is a string indicating what went wrong (in low-level terms).

You should report this to the author or maintainer of your Python interpreter. Be sure to report the version of the Python interpreter (sys.version;it is also printed at the start of an interactive Python session), the exact error message (the exception’s associated value) and if possible the source of the program that triggered the error.

exceptionSystemExit

This exception is raised by thesys.exit()function. It inherits from BaseExceptioninstead ofExceptionso that it is not accidentally caught by code that catchesException.This allows the exception to properly propagate up and cause the interpreter to exit. When it is not handled, the Python interpreter exits; no stack traceback is printed. The constructor accepts the same optional argument passed tosys.exit(). If the value is an integer, it specifies the system exit status (passed to C’sexit()function); if it isNone,the exit status is zero; if it has another type (such as a string), the object’s value is printed and the exit status is one.

A call tosys.exit()is translated into an exception so that clean-up handlers (finallyclauses oftrystatements) can be executed, and so that a debugger can execute a script without running the risk of losing control. Theos._exit()function can be used if it is absolutely positively necessary to exit immediately (for example, in the child process after a call toos.fork()).

code

The exit status or error message that is passed to the constructor. (Defaults toNone.)

exceptionTypeError

Raised when an operation or function is applied to an object of inappropriate type. The associated value is a string giving details about the type mismatch.

This exception may be raised by user code to indicate that an attempted operation on an object is not supported, and is not meant to be. If an object is meant to support a given operation but has not yet provided an implementation,NotImplementedErroris the proper exception to raise.

Passing arguments of the wrong type (e.g. passing alistwhen an intis expected) should result in aTypeError,but passing arguments with the wrong value (e.g. a number outside expected boundaries) should result in aValueError.

exceptionUnboundLocalError

Raised when a reference is made to a local variable in a function or method, but no value has been bound to that variable. This is a subclass of NameError.

exceptionUnicodeError

Raised when a Unicode-related encoding or decoding error occurs. It is a subclass ofValueError.

UnicodeErrorhas attributes that describe the encoding or decoding error. For example,err.object[err.start:err.end]gives the particular invalid input that the codec failed on.

encoding

The name of the encoding that raised the error.

reason

A string describing the specific codec error.

object

The object the codec was attempting to encode or decode.

start

The first index of invalid data inobject.

end

The index after the last invalid data inobject.

exceptionUnicodeEncodeError

Raised when a Unicode-related error occurs during encoding. It is a subclass of UnicodeError.

exceptionUnicodeDecodeError

Raised when a Unicode-related error occurs during decoding. It is a subclass of UnicodeError.

exceptionUnicodeTranslateError

Raised when a Unicode-related error occurs during translating. It is a subclass ofUnicodeError.

exceptionValueError

Raised when an operation or function receives an argument that has the right type but an inappropriate value, and the situation is not described by a more precise exception such asIndexError.

exceptionZeroDivisionError

Raised when the second argument of a division or modulo operation is zero. The associated value is a string indicating the type of the operands and the operation.

The following exceptions are kept for compatibility with previous versions; starting from Python 3.3, they are aliases ofOSError.

exceptionEnvironmentError

exceptionIOError

exceptionWindowsError

Only available on Windows.

OS exceptions

The following exceptions are subclasses ofOSError,they get raised depending on the system error code.

exceptionBlockingIOError

Raised when an operation would block on an object (e.g. socket) set for non-blocking operation. Corresponds toerrnoEAGAIN,EALREADY, EWOULDBLOCKandEINPROGRESS.

In addition to those ofOSError,BlockingIOErrorcan have one more attribute:

characters_written

An integer containing the number of characters written to the stream before it blocked. This attribute is available when using the buffered I/O classes from theiomodule.

exceptionChildProcessError

Raised when an operation on a child process failed. Corresponds toerrnoECHILD.

exceptionConnectionError

A base class for connection-related issues.

Subclasses areBrokenPipeError,ConnectionAbortedError, ConnectionRefusedErrorandConnectionResetError.

exceptionBrokenPipeError

A subclass ofConnectionError,raised when trying to write on a pipe while the other end has been closed, or trying to write on a socket which has been shutdown for writing. Corresponds toerrnoEPIPEandESHUTDOWN.

exceptionConnectionAbortedError

A subclass ofConnectionError,raised when a connection attempt is aborted by the peer. Corresponds toerrnoECONNABORTED.

exceptionConnectionRefusedError

A subclass ofConnectionError,raised when a connection attempt is refused by the peer. Corresponds toerrnoECONNREFUSED.

exceptionConnectionResetError

A subclass ofConnectionError,raised when a connection is reset by the peer. Corresponds toerrnoECONNRESET.

exceptionFileExistsError

Raised when trying to create a file or directory which already exists. Corresponds toerrnoEEXIST.

exceptionFileNotFoundError

Raised when a file or directory is requested but doesn’t exist. Corresponds toerrnoENOENT.

exceptionInterruptedError

Raised when a system call is interrupted by an incoming signal. Corresponds toerrnoEINTR.

Changed in version 3.5:Python now retries system calls when a syscall is interrupted by a signal, except if the signal handler raises an exception (seePEP 475 for the rationale), instead of raisingInterruptedError.

exceptionIsADirectoryError

Raised when a file operation (such asos.remove()) is requested on a directory. Corresponds toerrnoEISDIR.

exceptionNotADirectoryError

Raised when a directory operation (such asos.listdir()) is requested on something which is not a directory. On most POSIX platforms, it may also be raised if an operation attempts to open or traverse a non-directory file as if it were a directory. Corresponds toerrnoENOTDIR.

exceptionPermissionError

Raised when trying to run an operation without the adequate access rights - for example filesystem permissions. Corresponds toerrnoEACCES, EPERM,andENOTCAPABLE.

Changed in version 3.11.1:WASI’sENOTCAPABLEis now mapped to PermissionError.

exceptionProcessLookupError

Raised when a given process doesn’t exist. Corresponds toerrnoESRCH.

exceptionTimeoutError

Raised when a system function timed out at the system level. Corresponds toerrnoETIMEDOUT.

Added in version 3.3:All the aboveOSErrorsubclasses were added.

See also

PEP 3151- Reworking the OS and IO exception hierarchy

Warnings

The following exceptions are used as warning categories; see the Warning Categoriesdocumentation for more details.

exceptionWarning

Base class for warning categories.

exceptionUserWarning

Base class for warnings generated by user code.

exceptionDeprecationWarning

Base class for warnings about deprecated features when those warnings are intended for other Python developers.

Ignored by the default warning filters, except in the__main__module (PEP 565). Enabling thePython Development Modeshows this warning.

The deprecation policy is described inPEP 387.

exceptionPendingDeprecationWarning

Base class for warnings about features which are obsolete and expected to be deprecated in the future, but are not deprecated at the moment.

This class is rarely used as emitting a warning about a possible upcoming deprecation is unusual, andDeprecationWarning is preferred for already active deprecations.

Ignored by the default warning filters. Enabling thePython Development Modeshows this warning.

The deprecation policy is described inPEP 387.

exceptionSyntaxWarning

Base class for warnings about dubious syntax.

exceptionRuntimeWarning

Base class for warnings about dubious runtime behavior.

exceptionFutureWarning

Base class for warnings about deprecated features when those warnings are intended for end users of applications that are written in Python.

exceptionImportWarning

Base class for warnings about probable mistakes in module imports.

Ignored by the default warning filters. Enabling thePython Development Modeshows this warning.

exceptionUnicodeWarning

Base class for warnings related to Unicode.

exceptionEncodingWarning

Base class for warnings related to encodings.

SeeOpt-in EncodingWarningfor details.

Added in version 3.10.

exceptionBytesWarning

Base class for warnings related tobytesandbytearray.

exceptionResourceWarning

Base class for warnings related to resource usage.

Ignored by the default warning filters. Enabling thePython Development Modeshows this warning.

Added in version 3.2.

Exception groups

The following are used when it is necessary to raise multiple unrelated exceptions. They are part of the exception hierarchy so they can be handled withexceptlike all other exceptions. In addition, they are recognised byexcept*,which matches their subgroups based on the types of the contained exceptions.

exceptionExceptionGroup(msg,excs)

exceptionBaseExceptionGroup(msg,excs)

Both of these exception types wrap the exceptions in the sequenceexcs. Themsgparameter must be a string. The difference between the two classes is thatBaseExceptionGroupextendsBaseExceptionand it can wrap any exception, whileExceptionGroupextendsException and it can only wrap subclasses ofException.This design is so that exceptExceptioncatches anExceptionGroupbut not BaseExceptionGroup.

TheBaseExceptionGroupconstructor returns anExceptionGroup rather than aBaseExceptionGroupif all contained exceptions are Exceptioninstances, so it can be used to make the selection automatic. TheExceptionGroupconstructor, on the other hand, raises aTypeErrorif any contained exception is not an Exceptionsubclass.

message

Themsgargument to the constructor. This is a read-only attribute.

exceptions

A tuple of the exceptions in theexcssequence given to the constructor. This is a read-only attribute.

subgroup(condition)

Returns an exception group that contains only the exceptions from the current group that matchcondition,orNoneif the result is empty.

The condition can be either a function that accepts an exception and returns true for those that should be in the subgroup, or it can be an exception type or a tuple of exception types, which is used to check for a match using the same check that is used in anexceptclause.

The nesting structure of the current exception is preserved in the result, as are the values of itsmessage, __traceback__,__cause__, __context__and __notes__fields. Empty nested groups are omitted from the result.

The condition is checked for all exceptions in the nested exception group, including the top-level and any nested exception groups. If the condition is true for such an exception group, it is included in the result in full.

split(condition)

Likesubgroup(),but returns the pair(match,rest)wherematch issubgroup(condition)andrestis the remaining non-matching part.

derive(excs)

Returns an exception group with the samemessage,but which wraps the exceptions inexcs.

This method is used bysubgroup()andsplit(),which are used in various contexts to break up an exception group. A subclass needs to override it in order to makesubgroup() andsplit()return instances of the subclass rather thanExceptionGroup.

subgroup()andsplit()copy the __traceback__, __cause__,__context__and __notes__fields from the original exception group to the one returned byderive(),so these fields do not need to be updated byderive().

>>>classMyGroup(ExceptionGroup):
...defderive(self,excs):
...returnMyGroup(self.message,excs)
...
>>>e=MyGroup("eg",[ValueError(1),TypeError(2)])
>>>e.add_note("a note")
>>>e.__context__=Exception("context")
>>>e.__cause__=Exception("cause")
>>>try:
...raisee
...exceptExceptionase:
...exc=e
...
>>>match,rest=exc.split(ValueError)
>>>exc,exc.__context__,exc.__cause__,exc.__notes__
(MyGroup('eg', [ValueError(1), TypeError(2)]), Exception('context'), Exception('cause'), ['a note'])
>>>match,match.__context__,match.__cause__,match.__notes__
(MyGroup('eg', [ValueError(1)]), Exception('context'), Exception('cause'), ['a note'])
>>>rest,rest.__context__,rest.__cause__,rest.__notes__
(MyGroup('eg', [TypeError(2)]), Exception('context'), Exception('cause'), ['a note'])
>>>exc.__traceback__ismatch.__traceback__isrest.__traceback__
True

Note thatBaseExceptionGroupdefines__new__(),so subclasses that need a different constructor signature need to override that rather than__init__().For example, the following defines an exception group subclass which accepts an exit_code and and constructs the group’s message from it.

classErrors(ExceptionGroup):
def__new__(cls,errors,exit_code):
self=super().__new__(Errors,f"exit code:{exit_code}",errors)
self.exit_code=exit_code
returnself

defderive(self,excs):
returnErrors(excs,self.exit_code)

LikeExceptionGroup,any subclass ofBaseExceptionGroupwhich is also a subclass ofExceptioncan only wrap instances of Exception.

Added in version 3.11.

Exception hierarchy

The class hierarchy for built-in exceptions is:

BaseException
├── BaseExceptionGroup
├── GeneratorExit
├── KeyboardInterrupt
├── SystemExit
└── Exception
├── ArithmeticError
│ ├── FloatingPointError
│ ├── OverflowError
│ └── ZeroDivisionError
├── AssertionError
├── AttributeError
├── BufferError
├── EOFError
├── ExceptionGroup [BaseExceptionGroup]
├── ImportError
│ └── ModuleNotFoundError
├── LookupError
│ ├── IndexError
│ └── KeyError
├── MemoryError
├── NameError
│ └── UnboundLocalError
├── OSError
│ ├── BlockingIOError
│ ├── ChildProcessError
│ ├── ConnectionError
│ │ ├── BrokenPipeError
│ │ ├── ConnectionAbortedError
│ │ ├── ConnectionRefusedError
│ │ └── ConnectionResetError
│ ├── FileExistsError
│ ├── FileNotFoundError
│ ├── InterruptedError
│ ├── IsADirectoryError
│ ├── NotADirectoryError
│ ├── PermissionError
│ ├── ProcessLookupError
│ └── TimeoutError
├── ReferenceError
├── RuntimeError
│ ├── NotImplementedError
│ └── RecursionError
├── StopAsyncIteration
├── StopIteration
├── SyntaxError
│ └── IndentationError
│ └── TabError
├── SystemError
├── TypeError
├── ValueError
│ └── UnicodeError
│ ├── UnicodeDecodeError
│ ├── UnicodeEncodeError
│ └── UnicodeTranslateError
└── Warning
├── BytesWarning
├── DeprecationWarning
├── EncodingWarning
├── FutureWarning
├── ImportWarning
├── PendingDeprecationWarning
├── ResourceWarning
├── RuntimeWarning
├── SyntaxWarning
├── UnicodeWarning
└── UserWarning