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See all trending →HTTP 400 Bad Request
The server could not understand the request because its syntax, headers or body are malformed or invalid.
HTTP 403 Forbidden
The server understood the request but refuses to authorize it — you (or the server process) are not allowed to access this resour…
HTTP 500 Internal Server Error
The server hit an unexpected condition — usually an unhandled exception or misconfiguration in the application.
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).
Python requests: HTTPSConnectionPool(host='api.example.com', port=443): Max retries exceeded with url: /v1 (Caused by SSLError(SSLCertVerificationError(1, '[SSL: CERTIFICATE_VERIFY_FAILED] ...')))
The `requests` call failed during the TLS step and exhausted its retries; the real reason is in the nested SSLError text.
Go: panic: reflect: call of reflect.Value.Elem on zero Value
Reflection code operated on an invalid (zero) `reflect.Value`, often derived from a nil pointer or a missing struct field.
Python requests: HTTPSConnectionPool(host='api.example.com', port=443): Max retries exceeded with url: /v1 (Caused by SSLError(SSLCertVerificationError(1, '[SSL: CERTIFICATE_VERIFY_FAILED] ...')))
The `requests` call failed during the TLS step and exhausted its retries; the real reason is in the nested SSLError text.
TypeScript: error TS1005: ';' expected.
The parser hit a syntax error — missing punctuation, mismatched brackets, or an unsupported syntax for your TypeScript version.
Flutter: Looking up a deactivated widget's ancestor is unsafe. At this point the state of the widget's element tree is no longer stable
You used a `BuildContext` after its widget was removed from the tree — typically after an `await` when the user already navigated…
Bundler: Your Ruby version is 3.1.2, but your Gemfile specified 3.3.0
`.ruby-version`/the Gemfile `ruby` line requires a different Ruby than the one running.
ECS: Essential container in task exited (task keeps stopping)
The main (essential) container stopped, so ECS stopped the whole task and the service keeps replacing it.
MySQL ERROR 1062 (23000): Duplicate entry for key
An INSERT/UPDATE would create a duplicate value in a PRIMARY or UNIQUE key.
[nodemon] app crashed - waiting for file changes before starting...
Your app threw an error on startup; nodemon is waiting for a file change to retry.
Thread 1: signal SIGABRT (app crashes with "libc++abi: terminating")
The app deliberately aborted — an uncaught exception, failed assertion or fatalError. The console above the crash has the real me…
Jenkins: Still waiting to schedule task — Waiting for next available executor / 'agent1' is offline
A Jenkins build is queued because no executor with the required label is free or the agent is offline.
ERROR: prepared statement "s1" already exists (PgBouncer transaction mode)
Named prepared statements collided — typically because PgBouncer in transaction pooling mode hands connections between clients.
System has not been booted with systemd as init system (PID 1). Can't operate.
You ran systemctl inside an environment without systemd as PID 1 — a Docker container or older WSL.
Flutter: Unhandled Exception: SocketException: Failed host lookup: 'api.example.com' (OS Error: No address associated with hostname, errno = 7)
The app could not resolve or reach the server: no internet, wrong host name, DNS failure, or missing network permission.
Most looked-up errors
2,380 errors documentedHTTP 500 Internal Server Error
The server hit an unexpected condition — usually an unhandled exception or misconfiguration in the application.
HTTP 403 Forbidden
The server understood the request but refuses to authorize it — you (or the server process) are not allowed to access this resour…
HTTP 400 Bad Request
The server could not understand the request because its syntax, headers or body are malformed or invalid.
ORA-00933: SQL command not properly ended
Oracle found extra clauses or syntax it doesn’t support at the end of a statement.
MySQL ERROR 1064 (42000): You have an error in your SQL syntax
MySQL couldn’t parse the query. The text after “near” shows where parsing failed.
WordPress: There Has Been a Critical Error on This Website
A PHP fatal error (usually from a plugin or theme) stopped WordPress; the real error is in the debug log or recovery-mode email.
Could not load file or assembly 'X, Version=…' or one of its dependencies
The runtime couldn’t find or load a referenced DLL — missing from the output, wrong version, or wrong platform (x86/x64).
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…
Thread 1: signal SIGABRT (app crashes with "libc++abi: terminating")
The app deliberately aborted — an uncaught exception, failed assertion or fatalError. The console above the crash has the real me…
Console: SecurityError: Failed to read the 'localStorage' property from 'Window': Access is denied for this document
The page cannot use `localStorage` because cookies/site data are blocked, it runs in a sandboxed iframe, or the browser is in a r…
The application was unable to start correctly (0xc000007b)
A program loaded a DLL of the wrong architecture (32-bit vs 64-bit) or a corrupted runtime library.
HTTP 404 Not Found
The server can’t find anything at the requested URL.
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Paste a raw error, log line, HTTP response or stack trace. We detect the error code, platform and request, match it against our knowledge base, and tell you the likely cause and what to check first.
403 Forbidden nginx/1.24.0 GET /api/usersAnalyze an error
⚖️ Confusing pairs, explained
- 401 vs 403: Unauthorized vs Forbidden
- 301 vs 302: Permanent vs Temporary Redirect
- 400 vs 422: Bad Request vs Unprocessable Content
- Cloudflare 525 vs 526: SSL Handshake Failed vs Invalid SSL Certificate
- 406 vs 415: Not Acceptable vs Unsupported Media Type
- Authentication vs Authorization