ErrLookup › python/cpython
python/cpython
The Python programming language · Python · 2,160 source files
Analyzed at bc6749cc3b on 2026-08-14. 413 documented errors.
| Code / Message | Type | Severity | Tags |
|---|---|---|---|
| staggered race failed | exception | error | asyncio, network, concurrency, exception-group |
| Cannot locate working compiler | exception | error | macos, compiler, build, xcode, clang, environment |
| Don't know machine value for archs=%r | exception | error | macos, architecture, build, archflags, environment |
| lost sys.stderr\n | console | error | cpython, stderr, unhandled-exception, epipe, display |
| Invalid ISO string | exception | error | datetime, isoformat, fromisoformat, iso-week, valueerror, stdlib |
| locale changed during initialization | validation | error | python, strptime, locale, threading, race-condition, stdlib |
| Refusing to create an inheritance cycle | exception | error | abc, inheritance, cycle, subclass |
| module 'ast' has no attribute | exception | error | ast, deprecation, attributeerror, compatibility |
| expected argument | exception | error | argparse, cli, nargs, missing-value |
| Argument expected for the %ls options\n | console | error | cli, command-line, getopt, cpython, startup |
| Warning: failed setting the LC_CTYPE environment variable to | console | warning | locale, environment, cpython, startup |
| cannot switch state from | exception | error | asyncio, ssl, state-machine, internal-api, lifecycle |
| Creating _SSLProtocolTransport twice | exception | error | asyncio, ssl, internal-api, lifecycle, start-tls |
| malformed node or string | exception | error | ast, literal-eval, deserialization, valueerror |
| Forward reference must be an expression -- got | exception | error | python, typing, forward-reference, annotations, syntax |
| not allowed with argument | exception | error | argparse, cli, mutually-exclusive, argument-conflict |
| {e.strerror} | exception | error | python, io, buffered-writer, blockingioerror, nonblocking, eagain, partial-write |
| %s | console | warning | startup, getpath, cpython, environment, pythonhome |
| () takes no arguments | exception | error | warnings, deprecated, typeerror, constructor, stdlib |
| Unrecognized action (%r) in warnings.filters | exception | error | warnings, filters, internal-api, configuration |
| Error setting LC_CTYPE, skipping C locale coercion\n | console | warning | locale, environment, cpython, startup, utf-8 |
| Could not convert pre-site command to Unicode\n | console | error | cpython, startup, presite, memory, unicode |
| argument must be a multiple of 32, with a maximum of | exception | error | decimal, ieee754, context, validation, valueerror |
| Failed to encode latin1 string when unpickling a time… | exception | error | datetime, pickle, valueerror, python2-migration, encoding |
| category must be a Warning subclass | exception | error | warnings, validation, category, filters |
| invalid buffering size | exception | error | io, open, buffering, valueerror, defensive |
| Failed to fetch glossary.json | exception | error | asyncio, windows, transport, race-condition, subprocess |
| ignored explicit argument %r | exception | error | argparse, cli, option-syntax, bundled-options |
| pre-site failed:\n | console | error | cpython, startup, presite, import, debugging |
| Connect call failed | exception | error | asyncio, networking, tcp, connection-refused, oserror |
| invalid action | exception | error | warnings, validation, filters, configuration |
| embedded null character | validation | error | python, pyrepl, readline, history, null-byte |
| reuse_port not supported by socket module, SO_REUSEPORT… | exception | error | asyncio, sockets, so-reuseport, kernel-support, containers |
| tracemalloc: | console | warning | cpython, tracemalloc, debug-build, memory, internal |
| d3-flame-graph library failed to load | exception | error | asyncio, sendfile, windows, concurrency, transport |
| insufficient terminal (vertical) | console | error | python, pyrepl, terminfo, cursor-movement, terminal |
| panic!\n | console | warning | socket, getaddrinfo, network, cpython-internals |
| cannot compare naive and aware times | exception | error | datetime, time, typeerror, naive-vs-aware, comparison |
| Unimplemented ioctl request | exception | error | asyncio, udp, validation, datagram |
| fromutc() requires a non-None dst() result | exception | error | datetime, timezone, valueerror, fromutc, dst |
| result out of range | exception | error | datetime, overflowerror, date-arithmetic, range |
| is bound to a different event loop | exception | error | asyncio, event-loop, synchronization, lifetime |
| self.raw should implement RawIOBase: it should not raise… | exception | error | python, io, buffered-writer, runtimeerror, rawiobase, custom-stream, protocol-violation |
| timezone changed during initialization | exception | error | strptime, timezone, race-condition, locale, cpython |
| You must set server_hostname when using ssl without a host | exception | error | asyncio, tls, ssl, certificate-verification, validation |
| Cannot stringify annotation containing string formatting | exception | error | python, annotations, pep649, stringification, f-string |
| invalid choice: %(value)r, maybe you meant %(closest)r?… | exception | error | argparse, cli, choices, suggestions, difflib |
| Must run this script from the repo root | exception | warning | asyncio, socket, debug-mode, non-blocking |
| create_connection failed | exception | error | asyncio, network, exception-group, python312, connection |
| Connection lost | exception | error | asyncio, network, streams, connection-reset |
| fromutc() requires a non-None utcoffset() result | exception | error | datetime, timezone, valueerror, fromutc, utc-offset |
| terminal doesn't have the required | console | error | python, pyrepl, terminfo, terminal, environment |
| cannot convert string of len | validation | error | python, int, pylong, input-validation, valueerror |
| Minute, second, and microsecond must be 0 when hour is 24 | exception | error | datetime, time, fromisoformat, valueerror, duration |
| invalid literal for int() with base 10 | validation | error | python, int, parsing, valueerror, input-validation |
| Multiple exceptions | exception | error | asyncio, network, oserror, multi-address, connection |
| Not implemented | exception | error | asyncio, udp, typeerror, encoding, windows |
| await wasn't used with future | exception | error | asyncio, future, await, coroutine |
| no matching local address with | exception | error | asyncio, network, ipv6, dual-stack, oserror |
| Windows 10 TH2 or later required | console | warning | python, repl, pyrepl, windows, platform, startup |
| invalid %(type)s value: %(value)r | exception | error | argparse, cli, type-conversion, invalid-value |
| Node can't use cause without an exception. | validation | error | ast, codegen, ast-unparse, developer-error |
| category must be a Warning subclass, not | exception | error | warnings, validation, category |
| module has no attribute | exception | error | argparse, attributeerror, getattr, deprecation |
| posix_spawnattr_setbinpref failed to copy\n | console | critical | macos, cpython, posix-spawn, architecture, startup |
| Socket cannot be of type SSLSocket | exception | error | asyncio, ssl, tls, sockets, typeerror |
| tzinfo.tzname() must return None or string, not | exception | error | datetime, tzinfo, typeerror, timezone |
| Failed to encode latin1 string when unpickling a date… | exception | error | datetime, valueerror, pickle, serialization |
| bad tzinfo state arg | exception | error | datetime, time, pickle, typeerror, tzinfo-state |
| Cannot enter %r twice | exception | error | warnings, context-manager, state, testing |
| Expected long option\n | console | error | cli, getopt, command-line, cpython, argument-parsing |
| I/O operation on closed file. | exception | error | io, file, lifecycle, valueerror |
| @deprecated decorator with non-None category must be… | exception | error | warnings, deprecated, typeerror, decorator, stdlib |
| write() returned incorrect number of bytes | exception | error | python, io, buffered-writer, oserror, custom-stream, rawiobase, contract-violation |
| detach_thread: failed detaching thread\n | console | warning | threading, cpython, pthreads, interpreter-shutdown |
| invalid nargs value | exception | error | python, argparse, cli, nargs, validation |
| %r can't have docstrings | exception | error | ast, docstring, typeerror, introspection |
| Invalid address: must be None or | exception | error | asyncio, networking, udp, datagram, connected-socket, valueerror |
| Non-digit values in fraction | exception | error | datetime, fromisoformat, fraction, valueerror, stdlib |
| Unsupported format | exception | error | python, annotations, validation, format-enum |
| unknown declaration %r in internal subset | exception | error | markup, html-parser, dtd, doctype, parsing |
| key definitions for clash | validation | error | python, pyrepl, keymap, prefix-conflict, trie |
| Python detected LC_CTYPE=C: LC_CTYPE coerced to %.20s (set… | console | info | locale, cpython, startup, environment, utf-8 |
| Wrong field count in | validation | error | asyncio, queue, consumer, bookkeeping |
| sendfile is not supported for transport | exception | error | asyncio, sendfile, ssl, transport, unsupported-operation |
| tzinfo subclass must override dst() | exception | error | datetime, timezone, notimplementederror, dst |
| Invalid isoformat string | exception | error | datetime, time, valueerror, fromisoformat, parsing |
| can't open '%(filename)s': %(error)s | validation | error | python, argparse, cli, file-io, filetype, oserror |
| Incomplete time component | exception | error | datetime, fromisoformat, time-parsing, valueerror, stdlib |
| insufficient terminal (horizontal) | console | error | python, pyrepl, terminfo, cursor-movement, terminal |
| name ' ' is not defined | exception | error | annotations, typing, forwardref, nameerror, name-resolution, cpython |
| socket modifier keyword arguments can not be used when sock… | exception | error | asyncio, udp, datagram, api-misuse |
| Callable must be used as Callable[[arg, ...], result]. | exception | error | typing, collections-abc, type-hints, developer-error |
| Empty waiter is already set | exception | error | asyncio, networking, sendfile, internal-api, concurrency |
| expected name token at %r | exception | error | markup, html-parser, parsing, malformed-html |
| fromutc(): dt.dst gave inconsistent results; cannot convert | exception | error | datetime, timezone, valueerror, fromutc, dst, consistency |
| Inconsistent use of : in | exception | error | strptime, timezone, utc-offset, parsing, cpython |
| tzinfo subclass must override utcoffset() | exception | error | datetime, timezone, notimplementederror, utc-offset |
| unhandled errors in a TaskGroup | exception | error | asyncio, taskgroup, exception-group, structured-concurrency |
ENOTTY tty required | console | warning | python, repl, pyrepl, tty, stdin, startup |