Error map

TS2420: Class incorrectly implements interface TypeScript: error TS2420: Class 'Dog' incorrectly implements interface 'Animal'. Property 'speak' is missing in type 'Dog' but required in type 'Animal'

TypeScript · layer 1, On your device

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TS2420: Class incorrectly implements interface — TypeScript: error TS2420: Class 'Dog' incorrectly implements interface 'Animal'. Property 'speak' is missing in type 'Dog' but required in type 'Animal' (TypeScript)TS2420: Cla…TS2564 — TS2564: Property 'x' has no initializer and is not definitely assigned in the constructor (TypeScript)TS2564TS1259: Module can only be default-imported using the 'esModuleInterop' flag — TypeScript: error TS1259: Module '"express"' can only be default-imported using the 'esModuleInterop' flag (TypeScript)TS1259: Module can …TS1208: File cannot be compiled under '--isolatedModules' because it is considered a global script file — TypeScript: error TS1208: 'index.ts' cannot be compiled under '--isolatedModules' because it is considered a global script file. Add an import, export, or an empty 'export {}' statement (TypeScript)TS1208: File cannot…TS2416: Property in type is not assignable to the same property in base type — TypeScript: error TS2416: Property 'render' in type 'Child' is not assignable to the same property in base type 'Base' (TypeScript)TS2416: Property in…TS2430: Interface incorrectly extends interface — TypeScript: error TS2430: Interface 'B' incorrectly extends interface 'A'. Types of property 'x' are incompatible (TypeScript)TS2430: Interface i…TS1192: Module has no default export — TypeScript: error TS1192: Module '"./utils"' has no default export. (TypeScript)TS1192: Module has …TS1005: ';' expected / ',' expected (syntax error) — TypeScript: error TS1005: ';' expected. (TypeScript)TS1005: ';' expecte…TS1128: Declaration or statement expected — TypeScript: error TS1128: Declaration or statement expected. (TypeScript)TS1128: Declaration…Cannot find module './App.vue' or its corresponding type declarations — TypeScript: error TS2307: Cannot find module './App.vue' or its corresponding type declarations. (Vue)Cannot find module …AttributeError — AttributeError: 'X' object has no attribute 'y' (Python)AttributeErrorClassCastException — java.lang.ClassCastException: class A cannot be cast to class B (Java)ClassCastExceptionnot a constructor — TypeError: x is not a constructor (JavaScript)not a constructorERR_REQUIRE_ESM — Error [ERR_REQUIRE_ESM]: require() of ES Module not supported (Node.js)ERR_REQUIRE_ESMSyntaxError import — SyntaxError: Cannot use import statement outside a module (Node.js)SyntaxError importERR_IMPORT_ATTRIBUTE_MISSING — TypeError [ERR_IMPORT_ATTRIBUTE_MISSING]: Module needs an import attribute of "type: json" (Node.js)ERR_IMPORT_ATTRIBUT…ERR_PACKAGE_PATH_NOT_EXPORTED — Error [ERR_PACKAGE_PATH_NOT_EXPORTED]: Package subpath './x' is not defined by "exports" (Node.js)ERR_PACKAGE_PATH_NO…TS2531: Object is possibly 'null' — TypeScript: error TS2531: Object is possibly 'null'. (TypeScript)TS2531: Object is p…TS2551: Property does not exist. Did you mean — TypeScript: error TS2551: Property 'lenght' does not exist on type 'string'. Did you mean 'length'? (TypeScript)TS2551: Property do…TS2322 — TS2322: Type 'X' is not assignable to type 'Y' (TypeScript)TS2322TypeError: not a function — TypeError: x is not a function (JavaScript)TypeError: not a fu…TDZ — ReferenceError: Cannot access 'x' before initialization (JavaScript)TDZERR_UNKNOWN_FILE_EXTENSION — TypeError [ERR_UNKNOWN_FILE_EXTENSION]: Unknown file extension ".ts" (Node.js)ERR_UNKNOWN_FILE_EX…Unexpected token < — SyntaxError: Unexpected token '<' (HTML served instead of JavaScript) (JavaScript)Unexpected token <unexpected end of input — SyntaxError: Unexpected end of input (JavaScript)unexpected end of i…missing ) — SyntaxError: missing ) after argument list (JavaScript)missing )already declared — SyntaxError: Identifier 'x' has already been declared (JavaScript)already declaredawait outside async — SyntaxError: await is only valid in async functions and the top level bodies of modules (JavaScript)await outside asyncunexpected identifier — SyntaxError: Unexpected identifier (JavaScript)unexpected identifi…TS2307 — TS2307: Cannot find module 'x' or its corresponding type declarations. (Node.js)TS2307TS7016 — TS7016: Could not find a declaration file for module 'x'. 'x.js' implicitly has an 'any' type. (Node.js)TS7016TS2304 — TS2304: Cannot find name 'x'. (Node.js)TS2304

Directly related (9)

TS2564TypeScript

TS2564: Property 'x' has no initializer and is not definitely assigned in the constructor

With strictPropertyInitialization on, a class property declared without ? or a default isn’t set in the constructor.

TS1259: Module can only be default-imported using the 'esModuleInterop' flagTypeScript

TypeScript: error TS1259: Module '"express"' can only be default-imported using the 'esModuleInterop' flag

You default-import a CommonJS module that uses `export =`, but `esModuleInterop` isn't enabled.

TS1208: File cannot be compiled under '--isolatedModules' because it is considered a global script fileTypeScript

TypeScript: error TS1208: 'index.ts' cannot be compiled under '--isolatedModules' because it is considered a global script file. Add an import, export, or an empty 'export {}' statement

With `isolatedModules`, every file must be a module (have an import or export).

TS2416: Property in type is not assignable to the same property in base typeTypeScript

TypeScript: error TS2416: Property 'render' in type 'Child' is not assignable to the same property in base type 'Base'

A subclass overrides a member with an incompatible type.

TS2430: Interface incorrectly extends interfaceTypeScript

TypeScript: error TS2430: Interface 'B' incorrectly extends interface 'A'. Types of property 'x' are incompatible

An extending interface redefines a property with a type that isn't assignable to the base's.

TS1192: Module has no default exportTypeScript

TypeScript: error TS1192: Module '"./utils"' has no default export.

You used `import x from "./mod"` but the module only has named exports.

TS1005: ';' expected / ',' expected (syntax error)TypeScript

TypeScript: error TS1005: ';' expected.

The parser hit a syntax error — missing punctuation, mismatched brackets, or an unsupported syntax for your TypeScript version.

TS1128: Declaration or statement expectedTypeScript

TypeScript: error TS1128: Declaration or statement expected.

The parser found a token where a declaration or statement should start — usually stray braces/parentheses or code outside a funct…

Cannot find module './App.vue' or its corresponding type declarationsVue

TypeScript: error TS2307: Cannot find module './App.vue' or its corresponding type declarations.

TypeScript doesn't know what a `.vue` import is without a shim or Volar/`vue-tsc`.

Two steps away (22)

AttributeErrorPython

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

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

ClassCastExceptionJava

java.lang.ClassCastException: class A cannot be cast to class B

An object was cast to a type it isn’t.

not a constructorJavaScript

TypeError: x is not a constructor

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

ERR_REQUIRE_ESMNode.js

Error [ERR_REQUIRE_ESM]: require() of ES Module not supported

CommonJS code used `require()` on a package that is ES-module-only (node-fetch 3, chalk 5, nanoid 4, got 12…).

SyntaxError importNode.js

SyntaxError: Cannot use import statement outside a module

An `import` statement ran in a context treated as CommonJS (Node without "type": "module", a browser script without type="module"…

ERR_IMPORT_ATTRIBUTE_MISSINGNode.js

TypeError [ERR_IMPORT_ATTRIBUTE_MISSING]: Module needs an import attribute of "type: json"

An ES module imported a .json file without the required import attribute.

ERR_PACKAGE_PATH_NOT_EXPORTEDNode.js

Error [ERR_PACKAGE_PATH_NOT_EXPORTED]: Package subpath './x' is not defined by "exports"

You imported a deep path inside a package that its package.json "exports" field doesn’t expose.

TS2531: Object is possibly 'null'TypeScript

TypeScript: error TS2531: Object is possibly 'null'.

You used a value that can be `null` without checking it first (strictNullChecks).

TS2551: Property does not exist. Did you meanTypeScript

TypeScript: error TS2551: Property 'lenght' does not exist on type 'string'. Did you mean 'length'?

A property name is misspelled (TypeScript suggests the closest valid one).

TS2322TypeScript

TS2322: Type 'X' is not assignable to type 'Y'

You assigned a value whose type doesn’t match the declared type of the variable, property or return value.

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…).

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.

ERR_UNKNOWN_FILE_EXTENSIONNode.js

TypeError [ERR_UNKNOWN_FILE_EXTENSION]: Unknown file extension ".ts"

Node tried to run a TypeScript file as ESM without a TypeScript loader.

Unexpected token <JavaScript

SyntaxError: Unexpected token '<' (HTML served instead of JavaScript)

The browser loaded a .js file but received HTML (an error page or the SPA index.html).

unexpected end of inputJavaScript

SyntaxError: Unexpected end of input

The parser reached the end of the code (or JSON) while still expecting more — a missing } ) ] or empty JSON.

missing )JavaScript

SyntaxError: missing ) after argument list

A function call’s parentheses are unbalanced — often an unescaped quote or a missing comma/plus.

already declaredJavaScript

SyntaxError: Identifier 'x' has already been declared

The same let/const/class name was declared twice in the same scope.

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).

unexpected identifierJavaScript

SyntaxError: Unexpected identifier

The parser found a name where it expected punctuation — usually a missing comma, operator or quote.

TS2307Node.js

TS2307: Cannot find module 'x' or its corresponding type declarations.

TypeScript can’t resolve the import — the package isn’t installed, the path alias isn’t configured, or there are no types.

TS7016Node.js

TS7016: Could not find a declaration file for module 'x'. 'x.js' implicitly has an 'any' type.

The JavaScript package has no TypeScript types bundled and no @types package installed.

TS2304Node.js

TS2304: Cannot find name 'x'.

TypeScript doesn’t know an identifier — a missing import, missing type definitions (e.g. for Node or Jest globals), or a typo.