321 error codes for the browser platform
Akousa100The server has received the request headers and the client should proceed to send the request body.
101The server is switching protocols as requested by the client via an Upgrade header.
103The server sends preliminary response headers to allow the client to start preloading resources before the final response.
200The request has succeeded. The meaning of the success depends on the HTTP method used.
201The request has been fulfilled and a new resource has been created as a result.
202The request has been accepted for processing, but the processing has not been completed yet.
203The response has been modified by a transforming proxy and differs from what the origin server sent.
204The server successfully processed the request but is not returning any content in the response body.
205The server tells the client to reset the document view, such as clearing a form after submission.
206The server is delivering only part of the resource due to a Range header sent by the client.
300The request has more than one possible response and the user or user agent should choose one of them.
301The requested resource has been permanently moved to a new URL, and future requests should use the new URL.
302The requested resource temporarily resides at a different URL. Future requests should continue to use the original URL.
303The response to the request can be found at a different URL using a GET method.
304The resource has not been modified since the last request, so the client can use its cached copy.
305The requested resource must be accessed through the proxy specified in the Location header. This status code is deprecated.
307The request should be repeated with the same method at the URL in the Location header. Unlike 302, the request method must not change.
308The resource has permanently moved to a new URL, and the request method must not change when following the redirect.
400The server cannot process the request due to a client error, such as malformed syntax, invalid parameters, or corrupt data.
401The request requires user authentication. The client must provide valid credentials to access the resource.
402The request requires payment. This status code is reserved for future use but is used by some APIs to indicate billing issues.
403The server understood the request but refuses to authorize it. Unlike 401, re-authenticating will not help.
404The server cannot find the requested resource. The URL may be incorrect or the resource may have been deleted.
405The HTTP method used is not supported for the requested resource.
406The server cannot produce a response matching the list of acceptable values defined in the request's Accept headers.
407The client must first authenticate with the proxy before the request can be forwarded to the target server.
408The server timed out waiting for the client to complete the request.
409The request conflicts with the current state of the server resource.
410The resource is no longer available and has been permanently removed. Unlike 404, this indicates intentional removal.
411The server requires a Content-Length header in the request but none was provided.
412One or more conditions specified in the request headers evaluated to false on the server.
413The request body exceeds the size limit configured on the server.
414The request URL is longer than the server is willing to interpret.
415The server refuses the request because the Content-Type of the request body is not supported.
416The client requested a range that is not available for the given resource.
417The server cannot meet the expectation specified in the Expect request header.
418The server refuses the request because it is, permanently, a teapot. An April Fools' joke from RFC 2324.
421The request was directed at a server that is not able to produce a response for the combination of scheme and authority in the request URI.
422The server understands the content type and syntax but cannot process the contained instructions due to semantic errors.
425The server is unwilling to process a request that might be replayed, to avoid potential replay attacks.
426The server refuses to perform the request using the current protocol and requires the client to upgrade.
428The server requires the request to be conditional to prevent the 'lost update' problem.
429The user has sent too many requests in a given amount of time (rate limiting).
431The server refuses the request because one or more header fields are too large.
451The resource is unavailable due to legal demands, such as censorship or court orders.
500The server encountered an unexpected condition that prevented it from fulfilling the request.
501The server does not support the functionality required to fulfill the request.
502A gateway or proxy server received an invalid response from the upstream server.
503The server is temporarily unable to handle the request due to maintenance or overloading.
504A gateway or proxy server did not receive a timely response from the upstream server.
505The server does not support the HTTP protocol version used in the request.
511The client needs to authenticate to gain network access, typically for captive portals.
520Cloudflare received an unexpected or empty response from the origin server.
521The origin web server has refused the connection from Cloudflare.
522Cloudflare could not negotiate a TCP handshake with the origin server.
523Cloudflare could not reach the origin server, typically due to DNS issues.
524Cloudflare established a TCP connection but the origin server did not respond with an HTTP response in time.
525Cloudflare could not complete an SSL/TLS handshake with the origin server.
526Cloudflare could not validate the SSL certificate on the origin server.
527A Cloudflare Railgun connection error occurred between the Cloudflare edge and the Railgun listener.
TypeErrorA value is not of the expected type. This is the most common JavaScript error, occurring when an operation encounters a value of the wrong type.
TypeError: x is not a functionAn attempt was made to call a value as a function when it is not a function.
TypeError: Cannot read properties of undefined/nullAn attempt was made to access a property or method on undefined or null.
TypeError: Cannot set properties of undefined/nullAn attempt was made to set a property on undefined or null.
TypeError: x is not iterableA value that is not iterable was used where an iterable was expected, such as in a for...of loop or spread operator.
TypeError: x is not a constructorAn attempt was made to use the new keyword with a value that is not a constructor.
TypeError: Assignment to constant variableAn attempt was made to reassign a variable declared with const.
TypeError: Cannot convert undefined or null to objectA built-in method that expects an object received null or undefined instead.
TypeError: Reduce of empty array with no initial valueArray.reduce() was called on an empty array without providing an initial value.
TypeError: Cannot assign to read only propertyAn attempt was made to write to a property that is read-only, either because the object is frozen or the property is defined as non-writable.
ReferenceErrorA reference was made to a variable that does not exist in the current scope.
ReferenceError: x is not definedA variable was referenced that has not been declared in any accessible scope.
ReferenceError: Cannot access before initializationA variable declared with let or const was accessed before its declaration in the temporal dead zone.
ReferenceError: Invalid left-hand side in assignmentAn assignment was attempted to something that cannot be assigned to.
SyntaxErrorThe JavaScript engine encountered code that does not conform to the language syntax.
SyntaxError: Unexpected tokenThe parser encountered a token (character or keyword) that was not expected at that position in the code.
SyntaxError: Unexpected end of inputThe parser reached the end of the input while still expecting more code, usually due to unclosed brackets or strings.
SyntaxError: JSON.parse unexpected characterJSON.parse() encountered invalid JSON syntax, such as single quotes, trailing commas, or unquoted keys.
SyntaxError: Missing ) after argument listA function call is missing its closing parenthesis.
SyntaxError: Unterminated string literalA string literal is missing its closing quote.
SyntaxError: Illegal return statementA return statement was used outside of a function body.
SyntaxError: Identifier has already been declaredA variable with the same name was declared twice in the same scope using let or const.
SyntaxError: Cannot use import statement outside a moduleES module import syntax was used in a file that is not treated as a module.
SyntaxError: await is only valid in async functionsThe await keyword was used outside of an async function.
RangeErrorA value is not within the expected range, such as an invalid array length or exceeding the call stack size.
RangeError: Maximum call stack size exceededThe JavaScript call stack has been exhausted, usually due to infinite or excessively deep recursion.
RangeError: Invalid array lengthAn array was created with an invalid length, such as a negative number or a non-integer.
RangeError: Invalid dateAn invalid date string was passed to a Date method that requires a valid date.
RangeError: precision is out of rangeA precision value passed to toFixed(), toPrecision(), or toExponential() is outside the allowed range.
URIErrorA global URI handling function (decodeURIComponent, encodeURI) received a malformed URI.
EvalErrorAn error related to the global eval() function. This error is rarely encountered in modern JavaScript.
InternalError: too much recursionFirefox-specific error equivalent to RangeError: Maximum call stack size exceeded in Chrome/Node.js.
AggregateErrorAn error that wraps multiple errors, typically thrown when all promises in Promise.any() are rejected.
UnhandledPromiseRejectionA Promise was rejected but no .catch() handler or try-catch block was present to handle the rejection.
DOMException: The operation was abortedAn operation was canceled via an AbortController signal.
DOMException: NetworkErrorA network operation failed, typically during a fetch request when the network is unreachable.
DOMException: QuotaExceededErrorA storage operation exceeded the available quota for localStorage, IndexedDB, or other browser storage.
DOMException: SecurityErrorA security-sensitive operation was blocked by the browser's security policies.
DOMException: NotAllowedErrorA browser API call was blocked because it requires user interaction or permission that was not granted.
CORS Error: No Access-Control-Allow-OriginThe browser blocked a cross-origin request because the server did not include the required CORS headers.
CORS Error: Preflight request failedThe browser's CORS preflight OPTIONS request was rejected or returned invalid CORS headers.
TypeError: Converting circular structure to JSONJSON.stringify() encountered an object with circular references that cannot be serialized to JSON.
TypeError: Method called on incompatible receiverA method was called with a 'this' value that is not the expected type.
TypeError: Cannot delete property of objectAn attempt was made to delete a non-configurable property of an object in strict mode.
TypeError: Cannot convert a Symbol value to a stringAn implicit conversion of a Symbol to a string was attempted, which is not allowed.
TypeError: Cannot add property, object is not extensibleAn attempt was made to add a property to an object that has been made non-extensible.
SyntaxError: Applying delete to unqualified name in strict modeThe delete operator was used on a plain variable name in strict mode, which is not allowed.
SyntaxError: Missing initializer in const declarationA const variable was declared without an initial value.
SyntaxError: JSON.parse: bad parsingFirefox-specific error message for invalid JSON passed to JSON.parse().
DOMException: InvalidStateErrorAn operation was attempted on an object that is in an invalid state for that operation.
DOMException: DataCloneErrorAn object could not be cloned using the structured clone algorithm.
TS2304TypeScript cannot find a variable, function, or type with the specified name in the current scope.
TS2345The argument passed to a function is not compatible with the expected parameter type.
TS2339TypeScript cannot find the specified property on the given type.
TS2307TypeScript cannot find the module specified in an import or require statement.
TS2322A value of one type cannot be assigned to a variable or property of a different, incompatible type.
TS2531TypeScript warns that an expression could be null at runtime, and you are using it without checking.
TS2554The number of arguments passed to a function does not match the number of required parameters.
TS2769None of the function overload signatures match the provided arguments.
TS7006A function parameter has no type annotation and TypeScript cannot infer its type.
TS1005TypeScript expected a specific token (like a semicolon, comma, or bracket) but found something else.
TS6133A variable, import, or parameter is declared but its value is never read.
TS2365An arithmetic or comparison operator is used with incompatible types.
TS2305The specified export does not exist in the referenced module.
TS2740An object type is missing required properties that are expected by the target type.
TS18048TypeScript warns that a value could be undefined and you are using it without checking.
TS2532TypeScript warns that an object expression could be undefined at runtime.
TS2741A required property is missing from the object being assigned.
TS2551TypeScript cannot find the property but suggests a similar name that might be what you intended.
TS1002A string literal is missing its closing quote.
TS1003TypeScript expected an identifier (variable name, function name, etc.) but found something else.
TS1109TypeScript expected an expression but found a token that cannot start an expression.
TS1128TypeScript expected a declaration or statement but found an unexpected token.
TS2306The file referenced in an import statement is not recognized as a module.
TS2314A generic type was used with the wrong number of type arguments.
TS2344A type argument does not meet the constraint specified by the generic type parameter.
TS2349The expression being called is not a function or callable type.
TS2353An object literal contains a property that does not exist on the target type.
TS2355A function with a declared return type does not return a value in all code paths.
TS2366A function with a non-void return type does not have a return statement at the end.
TS2367A comparison between two values will always be false because their types have no overlap.
TS2393A function with the same name is implemented more than once.
TS2394A function overload signature is not compatible with the implementation signature.
TS2416A property in a derived class is not compatible with the same property in the base class.
TS2420A class declares that it implements an interface but does not provide all required members.
TS2451A variable declared with let or const is being redeclared in the same scope.
TS2454A variable is used before it has been assigned a value.
TS2488The type being iterated does not have a Symbol.iterator method.
TS2493You are accessing a tuple element at an index that does not exist.
TS2503TypeScript cannot find a namespace with the specified name.
TS2515A non-abstract class that extends an abstract class does not implement all abstract members.
TS2540You are trying to modify a property that is marked as readonly.
TS2555The function call has fewer arguments than the minimum required.
TS2556The function was called with more arguments than it accepts.
TS2558A generic type or function is used without providing required type arguments.
TS2565A class property with a definite assignment assertion (!) is never read.
TS2564A class property is not initialized in the constructor and has no default value.
TS2571You are trying to use a value of type unknown without first narrowing its type.
TS2578A @ts-expect-error directive is present but no error occurs on the next line.
TS2588You are trying to reassign a variable declared with const.
TS2612A property in a derived class conflicts with a getter/setter accessor in the base class.
TS2683The this keyword has an implicit any type because there is no contextual type.
TS2684The this context of a function does not match the expected this type.
TS2694The specified member does not exist in the given namespace.
TS2696A TypeScript-only feature is being used in a JavaScript file.
TS2705An async function requires a higher ECMAScript target to compile.
TS2792TypeScript cannot resolve a module subpath because the package's exports field does not allow it.
TS2300The same identifier is declared more than once in the same scope.
TS7030A function with a return type does not return a value in all possible code paths.
TS7031A destructured binding element has an implicit any type.
TS7005A variable has an implicit any type because TypeScript cannot infer its type.
TS7041The default export expression does not have a type annotation.
TS6196A parameter is declared but its value is never read within the function body.
TS18046A value of type unknown is used in a position that requires a more specific type.
TS2497A CommonJS module is being imported with named import syntax but only has a default export.
TS1259A CommonJS module requires esModuleInterop or allowSyntheticDefaultImports to be imported with default import syntax.
TS1375The await keyword is used inside a function that is not marked as async.
TS1378Top-level await can only be used when the module option is set to a supported module system.
TS2430An interface declares that it extends another interface but has incompatible properties.
TS2461A destructuring pattern expects an array type but the value is not an array.
TS2347Type arguments were provided to a function that is not generic.
TS2395Merged declarations for the same name have inconsistent export modifiers.
TS2790The delete operator requires the operand to be an optional property.
TS2739An object type is missing multiple required properties from the target type.
TS1046An await expression or other top-level construct requires the file to be a module.
TS1056Getter/setter accessors require a higher ECMAScript target version.
TS1064The Promise constructor must be called with the new keyword.
TS1068An unexpected token was found inside a declaration file or declare block.
TS1149An import declaration conflicts with the ambient context of the file.
TS1192The module you are importing does not have a default export.
TS1202The import = require() syntax cannot be used in an ES module.
TS2328Two construct signatures (new() calls) have incompatible types.
TS2352A type assertion between two types that have no overlap might be an error.
TS2448A variable declared with let or const is referenced before its declaration in the same block.
TS2459A destructured import references a member that is not exported from the module.
TS2464A computed property name in a type literal must be a simple expression.
TS2507The expression used with new is not a constructor type.
TS2538The type of the index expression is not valid for indexing the object.
TS2559The source type has no properties in common with the target type.
TS2589A recursive type reaches TypeScript's maximum instantiation depth.
TS2590The resulting type expression creates a union with too many members for TypeScript to represent.
TS2610A derived class defines a property where the base class has an accessor.
TS2786A component's return type is not compatible with JSX element types.
TS17004JSX fragments ('<'>...'<'/>) require a jsxFragmentFactory or React.Fragment to be available.
TS5097Two incompatible compiler options are set simultaneously in tsconfig.
TS5023An unrecognized option was found in tsconfig.json.
TS5075A compiler option requires a specific moduleResolution setting to be used.
TS1131TypeScript expected a property declaration or method signature but found something else.
TS1219Decorators require the experimentalDecorators compiler option to be enabled.
TS1270A decorator is placed before the export keyword, which is not allowed.
TS2775A type assertion function requires all parameter types to be explicitly annotated.
TS4111A property is accessed using a string index on a type that uses noPropertyAccessFromIndexSignature.
TS4058The return type of a function cannot be named without importing a type from another module.
TS4055The return type of an exported function references a private or non-exported type.
TS2698The spread operator (...) is used on a value that may not be an object type.
TS2362The left operand of an arithmetic expression must be a number or bigint type.
TS2363The right operand of an arithmetic expression must be a number or bigint type.
Invalid property valueThe value assigned to a CSS property is not valid for that property.
Unknown propertyThe CSS property name is not recognized by the browser.
Unexpected tokenThe CSS parser encountered an unexpected character or token.
Missing semicolonA semicolon is missing at the end of a CSS declaration.
Unrecognized at-ruleThe CSS parser does not recognize the @-rule.
Invalid selectorThe CSS selector syntax is not valid.
z-index stacking contextElements are not layering as expected despite z-index values being set.
Specificity conflictA CSS rule is not applied because a more specific selector overrides it.
Overflow hidden clippingContent is being clipped or hidden unexpectedly due to overflow settings.
Deprecated -webkit- prefixA -webkit- prefixed property is deprecated and should be replaced with the standard version.
Deprecated -moz- prefixA -moz- prefixed property is deprecated and should be replaced with the standard version.
Flex item overflowA flex item overflows its container because it cannot shrink enough.
Invalid grid templateThe grid-template-columns or grid-template-rows value has invalid syntax.
Invalid calc() expressionThe calc() function has a syntax error.
!important overuseExcessive use of !important makes styles difficult to override and maintain.
@font-face format errorThe @font-face declaration has an invalid format or missing properties.
Font loading failedA web font could not be loaded from the specified URL.
Invalid media queryThe media query syntax is not valid.
Invalid @keyframesThe @keyframes animation definition has a syntax error.
Undefined CSS variableA CSS custom property (variable) is referenced but not defined.
Circular CSS variableTwo or more CSS custom properties reference each other, creating a circular dependency.
Transition on displayA CSS transition is not working because the display property cannot be transitioned.
Invalid color functionA CSS color function (rgb, hsl, oklch, etc.) has invalid syntax.
Container query unsupportedThe browser does not support @container queries.
CSS nesting unsupportedThe browser does not support native CSS nesting syntax.
Missing closing braceA CSS rule block is missing its closing brace.
Duplicate selectorThe same selector appears multiple times in the stylesheet.
Shorthand property overrideA CSS shorthand property resets values previously set by longhand properties.
Margin collapseVertical margins between elements collapse into a single margin instead of adding together.
Invalid clamp() syntaxThe clamp() function has incorrect syntax or parameters.
aspect-ratio ignoredThe aspect-ratio property is not taking effect on the element.
@layer ordering issueCSS cascade layers are not applying styles in the expected order.
Subgrid unsupportedThe browser does not support the subgrid value for grid-template-columns or grid-template-rows.
CSS Paint API errorA CSS Paint Worklet failed to render or register.
Scroll snap not workingCSS scroll snapping is not behaving as expected.
:has() unsupportedThe browser does not support the :has() pseudo-class.
NXDOMAINThe DNS server reports that the domain name does not exist.
SERVFAILThe DNS server encountered an internal error while processing the query.
REFUSEDThe DNS server refused to answer the query.
DNS_TIMEOUTThe DNS query timed out without receiving a response.
ERR_CERT_AUTHORITY_INVALIDThe SSL/TLS certificate is issued by a certificate authority that is not trusted.
ERR_CERT_DATE_INVALIDThe SSL/TLS certificate has expired or is not yet valid.
SSL_ERROR_HANDSHAKE_FAILUREThe SSL/TLS handshake between client and server failed.
certificate_unknownThe server's certificate could not be verified for an unknown reason.
ERR_NAME_NOT_RESOLVEDThe hostname could not be resolved to an IP address in the browser.
ERR_CONNECTION_REFUSEDThe browser's connection attempt was actively refused by the server.
ERR_CONNECTION_TIMED_OUTThe browser's connection attempt timed out waiting for a server response.
ERR_SSL_PROTOCOL_ERRORAn error occurred during the SSL/TLS protocol exchange.
CORS: Missing Access-Control-Allow-OriginThe server's response does not include the required Access-Control-Allow-Origin header.
CORS: Preflight request failedThe CORS preflight OPTIONS request was rejected by the server.
CORS: Method not allowedThe HTTP method is not included in the Access-Control-Allow-Methods header.
CORS: Header not allowedA request header is not included in the Access-Control-Allow-Headers response.
Mixed Content BlockedAn HTTPS page is loading resources over insecure HTTP.
Content Security Policy violationA resource or action was blocked by the Content-Security-Policy header.
ERR_CERT_COMMON_NAME_INVALIDThe SSL certificate's subject name does not match the requested hostname.
ERR_CERT_REVOKEDThe SSL certificate has been revoked by the certificate authority.
ERR_HTTP2_PROTOCOL_ERRORAn error occurred in the HTTP/2 protocol communication.
ERR_QUIC_PROTOCOL_ERRORAn error occurred in the QUIC/HTTP/3 protocol communication.
ERR_INTERNET_DISCONNECTEDThe device does not have an active internet connection.
ERR_NETWORK_CHANGEDThe network configuration changed during the request.
ERR_TOO_MANY_REDIRECTSThe browser detected too many HTTP redirects (typically more than 20).
ERR_SSL_VERSION_OR_CIPHER_MISMATCHThe client and server cannot agree on a TLS version or cipher suite.
ERR_CONNECTION_CLOSEDThe connection was closed before the response was completed.
ERR_CONNECTION_RESETThe connection was forcibly reset during communication.
ERR_EMPTY_RESPONSEThe server did not send any data and closed the connection.
ERR_FAILEDA network request failed for a reason not covered by more specific error codes.
ERR_ABORTEDThe network request was cancelled before completion.
ERR_BLOCKED_BY_CLIENTA browser extension (typically an ad blocker) blocked the request.
WebSocket connection failedThe WebSocket connection could not be established or was interrupted.
AbortError: The operation was abortedA fetch request was cancelled via an AbortController signal.
ERR_PROXY_CONNECTION_FAILEDThe connection to the proxy server could not be established.
ERR_TUNNEL_CONNECTION_FAILEDThe CONNECT tunnel through a proxy server could not be established.
ERR_CACHE_MISSThe browser cache does not have the requested resource and a network request was expected.
ERR_INSUFFICIENT_RESOURCESThe browser has run out of resources to handle the network request.
DNS_PROBE_FINISHED_NXDOMAINChrome's DNS probe confirmed the domain does not exist.
Sec-Fetch blockedThe request was blocked based on Sec-Fetch-* metadata headers.
TS2783A spread argument in a function call must be a tuple type or passed to a rest parameter.
TS2820A JSX element type does not have any matching call or construct signatures.
TS1343The import/export syntax requires the file to be treated as a module.
TS2742The inferred type of a declaration cannot be named without a dependency that is not available.
TS18047TypeScript warns that a value could be null and you are using it without checking.
TS2810A JSX attribute expected a boolean value but received a different type.
TS2353An object literal passed directly to a function contains properties not in the expected type.
TS2339A prop is passed to a React component that does not accept it in its type definition.
TS2786The expression cannot be used as a JSX component because its return type is not valid.
TS1479The relative import path requires a file extension under Node.js ESM resolution.
TS2688TypeScript cannot find the type definition file specified in types or typeRoots.
TS4082The default export requires a type annotation when generating declaration files.
TS2669Module augmentation declarations must be in a file that is recognized as an external module.
TS2856A @ts-check comment is used in a TypeScript file where it has no effect.
position: sticky not workingThe element with position: sticky does not stick as expected.
backdrop-filter not renderingThe backdrop-filter property has no visible effect on the element.
gap not working in flexboxThe gap property does not create spacing in a flex container.
text-overflow: ellipsis not workingThe text-overflow: ellipsis property does not show an ellipsis for overflowing text.
ERR_CERTIFICATE_TRANSPARENCY_REQUIREDThe certificate does not meet Certificate Transparency requirements.
ERR_RESPONSE_HEADERS_TOO_BIGThe server's response headers exceed the browser's maximum allowed size.
ERR_CONTENT_LENGTH_MISMATCHThe actual response body size does not match the Content-Length header.
CORS: Credentials mode not supportedA cross-origin request with credentials fails because the server uses a wildcard origin.
CSP: Inline script/style blockedAn inline script or style was blocked by the Content Security Policy.
ERR_SSL_CLIENT_AUTH_CERT_NEEDEDThe server requires a client SSL certificate for authentication.
ERR_ADDRESS_UNREACHABLEThe target IP address or hostname cannot be reached from the browser.
ERR_BLOCKED_BY_RESPONSEThe browser blocked the response due to CORB, CORP, or other response-based security policies.
ERR_NETWORK_IO_SUSPENDEDNetwork I/O has been suspended, typically when the browser is throttled.
ERR_SSL_OBSOLETE_VERSIONThe server only supports TLS versions that are considered obsolete and insecure.