Error map
22021 ERROR: invalid byte sequence for encoding "UTF8": 0x00
PostgreSQL · layer 5, Data
Centre: this error. First ring: errors it is linked with (9). 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.
Directly related (9)
URIError: URI malformed
decodeURIComponent/decodeURI received an invalid percent-encoded sequence.
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…).
MySQL ERROR 1046 (3D000): No database selected
A query referenced tables without a database selected (no USE and no db in the connection).
TypeError: x is not a constructor
new was used with something that isn’t a class/constructor — usually a wrong import.
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).
MySQL ERROR 1153 (08S01): Got a packet bigger than 'max_allowed_packet' bytes
A single statement or row exceeded max_allowed_packet — big BLOBs, huge INSERTs or large dump lines.
UnicodeEncodeError: 'charmap' codec can't encode character '\u2192'
Python tried to write text in an encoding that can’t represent some characters — common in Windows consoles and files opened with…
Go: declared and not used: x / "fmt" imported and not used
Go refuses to compile code with unused local variables or unused imports.
ReferenceError: Cannot access 'x' before initialization
A let/const/class was used before its declaration line ran (temporal dead zone) — often a circular import.
Two steps away (27)
HTTP 404 Not Found
The server can’t find anything at the requested URL.
AbortError: The user aborted a request. / signal is aborted without reason
A fetch was cancelled through an AbortController (or the browser cancelled it).
TypeError: Failed to execute 'json' on 'Response': body stream already read
A fetch Response body was consumed twice (e.g. calling .text() then .json()).
Error: Cannot find module 'x' (MODULE_NOT_FOUND)
Node can’t resolve the module path — the package isn’t installed, or a relative path/extension is wrong.
TypeError: Cannot read properties of undefined (reading 'x')
You tried to access a property on a value that is `undefined` (or `null`) — usually data that hasn’t loaded yet or a wrong proper…
ReferenceError: x is not defined
Code refers to a variable or function name that doesn’t exist in the current scope.
OAuth Error: redirect_uri_mismatch
The redirect URI in your OAuth request doesn’t exactly match one registered for the client in the provider’s console.
hint: You have divergent branches and need to specify how to reconcile them.
Git 2.27+ asks you to choose merge, rebase or fast-forward-only when local and remote both have new commits.
error: gpg failed to sign the data — fatal: failed to write commit object
Commit signing is enabled but GPG couldn’t sign — no TTY for the passphrase, wrong key, or agent not running.
MySQL ERROR 1227 (42000): Access denied; you need (at least one of) the SUPER privilege(s) for this operation
The import or statement needs SUPER/SYSTEM_VARIABLES_ADMIN — typical with dumps containing DEFINER clauses or SET GLOBAL on manag…
MySQL ERROR 1273 (HY000): Unknown collation: 'utf8mb4_0900_ai_ci'
A dump from MySQL 8 uses a collation the target server (MySQL 5.7 / MariaDB) doesn’t support.
TypeError: Router.use() requires a middleware function but got a Object
app.use()/router.use() received an object instead of a function — usually a router module that wasn’t exported.
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.
java.nio.file.NoSuchFileException: /path/file
An NIO Files operation targeted a path that doesn’t exist.
java.nio.file.AccessDeniedException: /path
The OS denied a file operation to the Java process.
MySQL ERROR 2006 (HY000): MySQL server has gone away
The connection to MySQL was closed — usually by a timeout or a packet larger than `max_allowed_packet`.
MySQL ERROR 1049 (42000): Unknown database 'x'
The database named in the connection doesn’t exist on that server.
API Error: Invalid or unsupported API version
The API version you requested — in the URL, a header or the SDK config — doesn’t exist or has been retired.
AttributeError: 'X' object has no attribute 'y'
You accessed an attribute or method that doesn’t exist on that object type.
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.
ConnectionRefusedError: [Errno 111] Connection refused
Nothing is listening on the host/port Python tried to connect to.
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.
Error: Element type is invalid: expected a string (for built-in components) or a class/function (for composite components) but got: undefined
JSX referenced a component that is undefined — almost always a default/named import mismatch.
error CS0246: The type or namespace name 'X' could not be found (are you missing a using directive or an assembly reference?)
The compiler doesn’t know the type — missing using, missing NuGet package/project reference, or a target framework mismatch.
NameError: name 'x' is not defined
Python doesn’t know the name — it was never assigned/imported in this scope, or it’s misspelled.
SyntaxError: Identifier 'x' has already been declared
The same let/const/class name was declared twice in the same scope.
UnboundLocalError: cannot access local variable 'x' where it is not associated with a value
A function assigns to a variable somewhere, which makes it local everywhere in that function — so reading it before the assignmen…
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