Error map

UnicodeEncodeError UnicodeEncodeError: 'charmap' codec can't encode character '\u2192'

Python · layer 4, Application & API

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Centre: this error. First ring: errors it is linked with (7). Outer ring: what those are linked with. Colours show the layer of a request each error belongs to. Click any dot to re-centre the map on it; hover to follow its connections. The centre dot opens the error page.

1 · On your device 2 · Network 3 · Edge & web server 4 · Application & API 5 · Data
UnicodeEncodeError — UnicodeEncodeError: 'charmap' codec can't encode character '\u2192' (Python)UnicodeEnco…URIError — URIError: URI malformed (JavaScript)URIErrorConnectionRefusedError — ConnectionRefusedError: [Errno 111] Connection refused (Python)ConnectionRefusedEr…BOM output — Unexpected characters at the top of the page / headers already sent by BOM (PHP)BOM outputAttributeError — AttributeError: 'X' object has no attribute 'y' (Python)AttributeErrorUnicodeDecodeError — UnicodeDecodeError: 'utf-8' codec can't decode byte 0x92 in position 10: invalid start byte (Python)UnicodeDecodeError22021 — ERROR: invalid byte sequence for encoding "UTF8": 0x00 (PostgreSQL)22021Event loop is closed — RuntimeError: Event loop is closed (Python)Event loop is closed404 — HTTP 404 Not Found (HTTP)404AbortError — AbortError: The user aborted a request. / signal is aborted without reason (JavaScript)AbortErrorbody already used — TypeError: Failed to execute 'json' on 'Response': body stream already read (JavaScript)body already usedECONNREFUSED — Error: connect ECONNREFUSED 127.0.0.1:5432 (Node.js)ECONNREFUSED521 — Cloudflare Error 521: Web Server Is Down (Cloudflare)521ETIMEDOUT — API Request Timed Out (ETIMEDOUT / ReadTimeout / timeout of 30000ms exceeded) (API)ETIMEDOUTHeaders already sent — Warning: Cannot modify header information - headers already sent (PHP)Headers already sentCORS — CORS Error: No 'Access-Control-Allow-Origin' header is present (API)CORS411 — HTTP 411 Length Required (HTTP)411TypeError: not a function — TypeError: x is not a function (JavaScript)TypeError: not a fu…ImportError — ImportError: cannot import name 'x' from 'y' (Python)ImportErrorKeyError — KeyError: 'x' (Python)KeyErrorFileNotFoundException — java.io.FileNotFoundException: config.properties (No such file or directory) (Java)FileNotFoundExcepti…NoSuchFileException — java.nio.file.NoSuchFileException: /path/file (Java)NoSuchFileExceptionAccessDeniedException — java.nio.file.AccessDeniedException: /path (Java)AccessDeniedExcepti…not a constructor — TypeError: x is not a constructor (JavaScript)not a constructorTDZ — ReferenceError: Cannot access 'x' before initialization (JavaScript)TDZ1046 — MySQL ERROR 1046 (3D000): No database selected (MySQL)1046UnhandledPromiseRejection — Node.js: [UnhandledPromiseRejection] — This error originated either by throwing inside of an async function without a catch block (Node.js)UnhandledPromiseRej…await outside async — SyntaxError: await is only valid in async functions and the top level bodies of modules (JavaScript)await outside asyncTypeError arguments — TypeError: f() takes 1 positional argument but 2 were given (Python)TypeError arguments

Directly related (7)

URIErrorJavaScript

URIError: URI malformed

decodeURIComponent/decodeURI received an invalid percent-encoded sequence.

ConnectionRefusedErrorPython

ConnectionRefusedError: [Errno 111] Connection refused

Nothing is listening on the host/port Python tried to connect to.

BOM outputPHP

Unexpected characters at the top of the page / headers already sent by BOM

A UTF-8 byte-order mark (BOM) at the start of a PHP file is sent as output, breaking headers, JSON and images.

AttributeErrorPython

AttributeError: 'X' object has no attribute 'y'

You accessed an attribute or method that doesn’t exist on that object type.

UnicodeDecodeErrorPython

UnicodeDecodeError: 'utf-8' codec can't decode byte 0x92 in position 10: invalid start byte

Python read bytes that aren’t valid in the encoding it assumed (usually UTF-8).

22021PostgreSQL

ERROR: invalid byte sequence for encoding "UTF8": 0x00

Text contained bytes invalid in UTF-8 — often a NUL byte (0x00) or Latin-1/Windows-1252 data.

Event loop is closedPython

RuntimeError: Event loop is closed

Async code tried to use an event loop that has already been shut down.

Two steps away (21)

404HTTP

HTTP 404 Not Found

The server can’t find anything at the requested URL.

AbortErrorJavaScript

AbortError: The user aborted a request. / signal is aborted without reason

A fetch was cancelled through an AbortController (or the browser cancelled it).

body already usedJavaScript

TypeError: Failed to execute 'json' on 'Response': body stream already read

A fetch Response body was consumed twice (e.g. calling .text() then .json()).

ECONNREFUSEDNode.js

Error: connect ECONNREFUSED 127.0.0.1:5432

Nothing is listening at that host:port — the target service is down or you’re connecting to the wrong address.

521Cloudflare

Cloudflare Error 521: Web Server Is Down

Cloudflare couldn’t connect to your origin — the connection was refused.

ETIMEDOUTAPI

API Request Timed Out (ETIMEDOUT / ReadTimeout / timeout of 30000ms exceeded)

The client gave up waiting — either for the connection to open or for the response to arrive.

Headers already sentPHP

Warning: Cannot modify header information - headers already sent

You called `header()`, `setcookie()` or `session_start()` after output had already been sent to the browser.

CORSAPI

CORS Error: No 'Access-Control-Allow-Origin' header is present

The browser blocked a cross-origin request because the server’s response didn’t include the CORS headers allowing your site’s ori…

411HTTP

HTTP 411 Length Required

The server refuses a request with a body but no Content-Length header.

TypeError: not a functionJavaScript

TypeError: x is not a function

You called something as a function, but its value is not a function (it’s undefined, a string, an object…).

ImportErrorPython

ImportError: cannot import name 'x' from 'y'

The module was found, but the name you’re importing from it doesn’t exist — usually a version change or a circular import.

KeyErrorPython

KeyError: 'x'

You accessed a dictionary key that doesn’t exist.

FileNotFoundExceptionJava

java.io.FileNotFoundException: config.properties (No such file or directory)

Java couldn’t open the file — wrong path relative to the working directory, missing file, or a classpath resource read as a file.

NoSuchFileExceptionJava

java.nio.file.NoSuchFileException: /path/file

An NIO Files operation targeted a path that doesn’t exist.

AccessDeniedExceptionJava

java.nio.file.AccessDeniedException: /path

The OS denied a file operation to the Java process.

not a constructorJavaScript

TypeError: x is not a constructor

new was used with something that isn’t a class/constructor — usually a wrong import.

TDZJavaScript

ReferenceError: Cannot access 'x' before initialization

A let/const/class was used before its declaration line ran (temporal dead zone) — often a circular import.

1046MySQL

MySQL ERROR 1046 (3D000): No database selected

A query referenced tables without a database selected (no USE and no db in the connection).

UnhandledPromiseRejectionNode.js

Node.js: [UnhandledPromiseRejection] — This error originated either by throwing inside of an async function without a catch block

A promise rejected and nothing handled it; since Node 15 this crashes the process.

await outside asyncJavaScript

SyntaxError: await is only valid in async functions and the top level bodies of modules

await was used inside a function that isn’t async (or in a classic, non-module script).

TypeError argumentsPython

TypeError: f() takes 1 positional argument but 2 were given

A function was called with more positional arguments than it accepts — very often a method missing `self`.

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