Error map
AH00558 Apache: AH00558: apache2: Could not reliably determine the server's fully qualified domain name
Nginx / Apache · layer 3, Edge & web server
Centre: this error. First ring: errors it is linked with (12). 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 (12)
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.
Nginx: nginx: [emerg] unknown directive "x" in /etc/nginx/sites-enabled/x:12 — configuration file test failed
Nginx found a directive it doesn’t know — a typo, a missing semicolon on the previous line, a directive from a module that isn’t…
django.core.exceptions.DisallowedHost: Invalid HTTP_HOST header: 'x'. You may need to add 'x' to ALLOWED_HOSTS.
The request’s Host header isn’t listed in Django’s ALLOWED_HOSTS.
perl: warning: Setting locale failed / bash: warning: setlocale: LC_ALL: cannot change locale
Your session asks for a locale (often forwarded by SSH from your Mac/PC) that isn’t generated on the server.
ReferenceError: React is not defined / 'React' must be in scope when using JSX
JSX was compiled with the classic runtime, which needs React imported in every file.
MySQL ERROR 1046 (3D000): No database selected
A query referenced tables without a database selected (no USE and no db in the connection).
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.
Failed to configure a DataSource: 'url' attribute is not specified and no embedded datasource could be configured.
Spring Boot found JDBC/JPA on the classpath but no database URL.
MySQL ERROR 1049 (42000): Unknown database 'x'
The database named in the connection doesn’t exist on that server.
WordPress: Error Establishing a Database Connection
WordPress can’t connect to its MySQL/MariaDB database with the credentials in wp-config.php, or the database server is down.
Laravel: No application encryption key has been specified.
Laravel’s APP_KEY is missing, so it can’t encrypt sessions and cookies.
Two steps away (36)
Azure AD (Entra ID): AADSTS700016 Application not found in the directory
The client ID in your sign-in request doesn’t exist in the tenant you’re authenticating against.
HTTP 400 Bad Request
The server could not understand the request because its syntax, headers or body are malformed or invalid.
OAuth 2.0 Error: invalid_grant
The authorization code, refresh token or credentials sent to the token endpoint are invalid, expired, already used or were issued…
HTTP 413 Content Too Large (Request Entity Too Large)
The request body is bigger than the server is willing to accept — usually a file upload over the configured limit.
Kubernetes: CreateContainerConfigError — secret / configmap not found
Kubernetes can’t build the container’s configuration — usually a referenced Secret, ConfigMap or key doesn’t exist in that namesp…
Author identity unknown *** Please tell me who you are.
Git doesn’t know your name and email for commits.
Python was not found; run without arguments to install from the Microsoft Store
Windows ran the Microsoft Store “App execution alias” instead of a real Python installation.
django.db.utils.OperationalError: no such table: app_model
Django queried a table that hasn’t been created — migrations missing or not applied.
django.core.exceptions.ImproperlyConfigured: settings are not configured / SECRET_KEY must not be empty
Django can’t load its settings — DJANGO_SETTINGS_MODULE unset, a required setting missing, or an environment variable not provide…
bash: command not found
The shell can’t find an executable with that name in any directory on your PATH.
ssh: connect to host x port 22: Connection refused
The server answered, but nothing is listening on the SSH port — sshd isn’t running, it uses another port, or a firewall actively…
ssh: connect to host x port 22: Connection timed out
SSH packets get no reply — a firewall/security group drops them, the server is off, or the IP is wrong.
ReferenceError: x is not defined
Code refers to a variable or function name that doesn’t exist in the current scope.
Error: Objects are not valid as a React child
You tried to render a plain object (or a Promise/Date) directly in JSX; React can only render strings, numbers, elements and arra…
Error: Nothing was returned from render. This usually means a return statement is missing.
A component returned undefined (React 17 and earlier) — usually a missing return or a return followed by a line break.
TypeError: x is not a constructor
new was used with something that isn’t a class/constructor — usually a wrong import.
ReferenceError: Cannot access 'x' before initialization
A let/const/class was used before its declaration line ran (temporal dead zone) — often a circular import.
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.
fatal: Not possible to fast-forward, aborting.
pull is configured to fast-forward only, but your branch and the remote have diverged.
warning: in the working copy of 'x', LF will be replaced by CRLF the next time Git touches it
Git’s line-ending conversion (core.autocrlf) will change line endings in your working copy.
TypeError [ERR_INVALID_ARG_TYPE]: The "path" argument must be of type string. Received undefined
A Node API got an argument of the wrong type — usually undefined because an env var or config value is missing.
Android: INSTALL_FAILED_UPDATE_INCOMPATIBLE
An app with the same package name but a different signing key is already installed on the device.
AWS: SignatureDoesNotMatch / InvalidClientTokenId — the request signature we calculated does not match
AWS rejected the request signature — wrong secret key, wrong region, clock skew, or a presigned URL used differently from how it…
npm update check failed — Try running with sudo or get access to the local update config store
npm’s update notifier couldn’t write its config — usually root-owned files in ~/.config from a past sudo npm.
UnsatisfiedDependencyException / NoSuchBeanDefinitionException: No qualifying bean of type 'X' available
Spring couldn’t find (or choose) a bean to inject.
The dependencies of some of the beans in the application context form a cycle
Two or more Spring beans depend on each other through constructors, and Spring Boot 2.6+ forbids cycles by default.
Web server failed to start. Port 8080 was already in use.
Spring Boot couldn’t bind its embedded server port because another process uses it.
MySQL ERROR 1045 (28000): Access denied for user
MySQL rejected the login — wrong password, wrong user/host combination, or the user doesn’t exist.
MySQL ERROR 2002 (HY000): Can't connect to local MySQL server through socket
The client couldn’t reach the MySQL server — it isn’t running, or the client is looking for the socket/port in the wrong place.
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`.
HTTP 500 Internal Server Error
The server hit an unexpected condition — usually an unhandled exception or misconfiguration in the application.
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.
MySQL ERROR 1040 (08004): Too many connections
MySQL reached `max_connections` and refuses new clients.
Warning: file_exists(): open_basedir restriction in effect. File(/x) is not within the allowed path(s)
PHP is configured to access only certain directories, and the script tried to touch a file outside them.
Laravel: 419 Page Expired (CSRF token mismatch)
Laravel rejected a POST because the CSRF token was missing, expired or didn’t match the session.
Laravel: Target class [App\Http\Controllers\X] does not exist.
Laravel’s container couldn’t find the controller or class named in a route or binding.
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