Error map
ActiveRecord::RecordInvalid: Validation failed Rails: ActiveRecord::RecordInvalid: Validation failed: Email can't be blank, Name is too short
Ruby / Rails · layer 4, Application & API
Centre: this error. First ring: errors it is linked with (11). 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 (11)
Rails: ActiveRecord::RecordNotFound: Couldn't find User with 'id'=42
`find`/`find_by!` didn't find a row, so Rails raises (and renders a 404 in production).
FactoryBot: FactoryBot::DuplicateDefinitionError: Factory already registered: user
Two factory definitions use the same name (or files are loaded twice).
Rails: ActiveRecord::RecordNotUnique: PG::UniqueViolation: ERROR: duplicate key value violates unique constraint "index_users_on_email"
A unique index rejected an insert/update because the value already exists.
Rails: ActiveRecord::ConnectionNotEstablished: No connection pool for 'ActiveRecord::Base' found
ActiveRecord has no database connection configured or established for this process.
Rails: ActiveRecord::Deadlocked: PG::TRDeadlockDetected: ERROR: deadlock detected
Two transactions locked rows in opposite orders, so PostgreSQL aborted one.
Rails: ActiveModel::ForbiddenAttributesError
You passed raw `params` to `new/create/update`, but strong parameters require permitting attributes first.
Rails: PG::ConnectionBad: could not connect to server: Connection refused. Is the server running on host "localhost" (127.0.0.1) and accepting TCP/IP connections on port 5432?
Rails can't reach PostgreSQL — the server is down, wrong host/port/socket, or credentials/pg_hba block it.
Rails: ActiveRecord::ReadOnlyRecord: Order is marked as readonly
You tried to save a record that was loaded as read-only (e.g. via `joins` in old Rails or `readonly` scope).
Rails: ActionController::ParameterMissing: param is missing or the value is empty: user
`params.require(:user)` found no `user` key (or it was blank), so Rails responds 400.
RSpec: expected: 200 got: 404 (compared using ==) — RSpec::Expectations::ExpectationNotMetError
An RSpec `expect` assertion didn't hold: the actual value differs from what the test expected.
Rails: ActiveRecord::AssociationTypeMismatch: User(#1234) expected, got "42" which is an instance of String(#5678)
You assigned the wrong kind of object (or an id string) to an association.
Two steps away (29)
Ruby: NoMethodError: undefined method `x' for nil (nil:NilClass)
You called a method on nil — the object you expected (a record, hash value, param) wasn’t there.
Rails: ActionController::RoutingError (No route matches [GET] "/users/new")
The request path/method doesn't match any route in `config/routes.rb` (a 404 in production).
Ruby: ArgumentError: wrong number of arguments (given 1, expected 2..3)
A method was called with more or fewer arguments than it accepts.
Ruby: ArgumentError: missing keyword: :name / unknown keyword: :nmae
A method requiring keyword arguments was called without them, or with a misspelt keyword.
Ruby: TypeError: nil can't be coerced into Integer / String can't be coerced into Integer
Arithmetic combined a number with `nil` (or a String) which Ruby can't convert automatically.
MySQL ERROR 1062 (23000): Duplicate entry for key
An INSERT/UPDATE would create a duplicate value in a PRIMARY or UNIQUE key.
MySQL ERROR 1452: Cannot add or update a child row: a foreign key constraint fails
You inserted/updated a row whose foreign key value doesn’t exist in the referenced parent table.
PostgreSQL: ERROR: duplicate key value violates unique constraint
An INSERT/UPDATE would create a duplicate in a UNIQUE or PRIMARY KEY column — or the id sequence is behind the existing data.
Rails: ActionController::InvalidAuthenticityToken (Can't verify CSRF token authenticity)
A non-GET request arrived without a valid CSRF token for the session.
Redis: Error: connect ECONNREFUSED 127.0.0.1:6379 / Could not connect to Redis at 127.0.0.1:6379: Connection refused
Nothing is listening on the Redis host/port your client uses.
Redis: Error: write EPROTO ... SSL routines:ssl3_get_record:wrong version number / Connection reset by peer (TLS vs plaintext)
The client and server disagree about TLS — plaintext client to a TLS port, or TLS client to a plaintext port.
Ruby: NameError: uninitialized constant UsersController::User (Did you mean? Users)
Ruby (or Rails autoloading) couldn't find a class or module with that name in the current scope.
Ruby: NameError: undefined local variable or method 'x' for main:Object
Ruby saw a bare identifier that is neither a local variable nor a method on the current object.
Rails: ActiveRecord::StatementInvalid: PG::UndefinedTable: ERROR: relation "users" does not exist
Rails queried a table that isn't in the connected PostgreSQL database.
WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! (ssh host key changed)
The server’s SSH host key differs from the one saved in ~/.ssh/known_hosts — usually because the server was rebuilt or the IP was…
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY
apt can’t verify a repository’s signature because the repo’s signing key isn’t installed (or has expired/rotated).
SELinux is preventing ... / avc: denied { read } for pid=... (permission denied despite correct permissions)
SELinux blocked the access — file permissions look fine, but the file’s security context or a boolean doesn’t allow the service t…
Rails: ActiveRecord::StatementInvalid: Mysql2::Error: Unknown column 'users.nickname' in 'field list'
The query references a column that doesn't exist in the table (missing migration, typo or stale schema cache).
Rails: ActiveRecord::StatementInvalid: PG::DuplicateColumn: ERROR: column "status" of relation "orders" already exists
A migration tried to add a column/table/index that already exists.
Rails: ActiveRecord::IrreversibleMigration — This migration uses remove_column without a type; db:rollback can't reverse it
`rails db:rollback` can't undo the migration because it contains an operation Rails can't invert.
Rails: ActiveRecord::StaleObjectError: Attempted to update a stale object: Order
Two users/processes updated the same record; the second save failed the `lock_version` check.
Rails: ActionController::UnknownFormat — UsersController#show is missing a template for this request format and variant
The controller has no template or `respond_to` handler for the requested format (HTML/JSON/etc.).
Rails: AbstractController::DoubleRenderError (Render and/or redirect were called multiple times in this action. Please note that you may only call render OR redirect, and at most once per action)
An action called `render`/`redirect_to` more than once.
Bundler: Could not find gem 'rails (~> 7.1)' in locally installed gems / Could not find rails-7.1.0 in any of the gem sources listed in your Gemfile
A gem from the Gemfile/Gemfile.lock isn't installed (or isn't available at that version).
Bundler: Bundler could not find compatible versions for gem "activesupport": In Gemfile: rails (= 7.1.0) depends on activesupport (= 7.1.0)
Two gems in your Gemfile require incompatible versions of a shared dependency.
Rake: rake aborted! Don't know how to build task 'db:migrat' (See the list of available tasks with `rake --tasks`)
Rake doesn't know the task name — a typo, a missing Rakefile, or a gem/engine not loaded.
Rails: ActiveRecord::PendingMigrationError — Migrations are pending. To resolve this issue, run: bin/rails db:migrate
The database schema is behind the migration files in the app.
Rails: ActionController::UrlGenerationError: No route matches {:action=>"show", :controller=>"users", :id=>nil}, missing required keys: [:id]
A URL helper (`user_path(@user)`) was called without a value Rails needs (usually `nil` object).
Rails: ActionView::MissingTemplate (Missing template users/show, application/show with {:locale=>[:en], :formats=>[:html], :handlers=>[:erb, :builder, :raw, :ruby, :jbuilder]})
The action tried to render a view that doesn't exist for the requested format/handler.
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