Error map
unexpected_state API Error: Invalid state transition — operation not allowed in the resource’s current state
API · layer 4, Application & API
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)
HTTP 422 Unprocessable Content
The request is well-formed, but the data fails validation (e.g. invalid email, missing required field).
Flutter: setState() called after dispose(): _MyState#1a2b3 (lifecycle state: defunct, not mounted)
An async callback (network, timer, stream) finished after the widget was removed and then called setState.
java.lang.IllegalStateException
A method was called when the object wasn’t in the right state for it.
Terraform: Error: Error acquiring the state lock — ConditionalCheckFailedException / state blob is already locked
Another Terraform run holds the state lock, or a previous run crashed and left the lock behind.
Warning: Cannot update a component (`Parent`) while rendering a different component (`Child`)
A child component updated a parent’s state during its render instead of in an effect or event handler.
Error: Maximum update depth exceeded. This can happen when a component repeatedly calls setState inside componentWillUpdate or componentDidUpdate.
A component keeps updating itself in an effect or lifecycle — usually a useEffect that sets state its own dependencies change.
Optimistic lock conflict: OptimisticLockException / StaleObjectStateException / version mismatch
Someone else changed the record after you read it, so your update — based on an old version — was rejected to avoid overwriting t…
HTTP 409 Conflict
The request conflicts with the current state of the resource — e.g. a duplicate or an edit based on an outdated version.
Error: Too many re-renders. React limits the number of renders to prevent an infinite loop.
A state update runs during render, which triggers another render, which updates state again — forever.
Warning: A component is changing an uncontrolled input to be controlled
An input’s `value` started as `undefined` (uncontrolled) and later became a defined value (controlled), or vice versa.
Error: Actions must be plain objects. Instead, the actual type was: 'function'.
A function (thunk) was dispatched but the thunk middleware isn’t configured.
A non-serializable value was detected in the state / in an action, in the path
Redux Toolkit’s middleware found a Date, Promise, class instance or function in state or an action.
Two steps away (32)
HTTP 400 Bad Request
The server could not understand the request because its syntax, headers or body are malformed or invalid.
HTTP 415 Unsupported Media Type
The server refuses the request because the body’s Content-Type isn’t one it accepts.
MySQL ERROR 1406: Data too long for column
The value is longer than the column allows (e.g. 300 characters into VARCHAR(255)), and strict mode rejects it instead of truncat…
TypeError: Cannot assign to read only property 'x' of object
Code tried to modify a frozen object, a getter-only property, or immutable state.
WindowManager$BadTokenException: Unable to add window -- token null is not valid; is your activity running?
A dialog or popup was shown with a context whose Activity is finishing/destroyed, or with the Application context.
IllegalStateException: Can not perform this action after onSaveInstanceState (fragment transaction)
A FragmentTransaction (or DialogFragment.show/navigation) ran after the Activity saved its state, typically from an async callbac…
java.lang.IllegalArgumentException
A method rejected an argument value as invalid.
java.lang.ArithmeticException: / by zero
Integer division or modulo by zero.
java.util.NoSuchElementException: No value present
Code asked for an element that doesn’t exist — Optional.get() on empty, iterator.next() past the end, Scanner with no input.
Deadlock found when trying to get lock; try restarting transaction
Two transactions waited on each other’s locks; the database killed one so the other could continue.
Lock wait timeout exceeded; try restarting transaction (MySQL 1205)
A query waited too long for a row lock held by another transaction and gave up.
MySQL ERROR 1213 (40001): Deadlock found when trying to get lock; try restarting transaction
MySQL detected a deadlock between two transactions and rolled one back.
Warning: Each child in a list should have a unique "key" prop
When rendering a list with `.map()`, each element needs a stable, unique `key` so React can track items between renders.
Error: Element type is invalid: expected a string (for built-in components) or a class/function (for composite components) but got: undefined
JSX referenced a component that is undefined — almost always a default/named import mismatch.
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.
Error: Invalid hook call. Hooks can only be called inside of the body of a function component.
A hook ran outside a function component/custom hook, conditionally — or two copies of React are loaded.
React Hook useEffect has a missing dependency (react-hooks/exhaustive-deps)
ESLint warns that the effect reads a value that isn’t in its dependency array, so it may use a stale value.
Warning: useEffect must not return anything besides a function, which is used for clean-up. It looks like you wrote useEffect(async () => ...)
An async function was passed directly to useEffect, so it returns a Promise instead of a cleanup function.
java.util.ConcurrentModificationException
A collection was modified while being iterated (even in a single thread).
HTTP 412 Precondition Failed
A conditional request header (If-Match, If-Unmodified-Since) didn’t match the current state of the resource.
HTTP 428 Precondition Required
The server requires a conditional request (If-Match / If-Unmodified-Since) to prevent lost updates, and you didn’t send one.
MySQL ERROR 1062 (23000): Duplicate entry for key
An INSERT/UPDATE would create a duplicate value in a PRIMARY or UNIQUE key.
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.
java.lang.InterruptedException (sleep interrupted)
A blocked thread (sleep, wait, join, queue take) was interrupted by another thread.
RangeError: Maximum call stack size exceeded
A function called itself (directly or indirectly) too many times — usually infinite recursion.
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…
Warning: Functions are not valid as a React child. This may happen if you return a Component instead of <Component /> from render.
A function (usually a component itself) was rendered instead of calling/rendering it as an element.
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…
Warning: validateDOMNesting(...): <div> cannot appear as a descendant of <p>.
The JSX produces invalid HTML nesting, which also causes hydration mismatches in SSR.
Error: No QueryClient set, use QueryClientProvider to set one
TanStack Query hooks ran outside a QueryClientProvider (or a duplicate copy of the library is installed).
android.os.TransactionTooLargeException: data parcel size x bytes
Too much data was put into a Bundle/Intent/saved state, exceeding the ~1 MB Binder transaction buffer.
SwiftUI: Modifying state during view update, this will cause undefined behavior
A @State/@Published value was changed while SwiftUI was computing a view’s body.
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