Error map
IllegalStateException java.lang.IllegalStateException
Java · 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)
System.InvalidCastException: Unable to cast object of type 'X' to type 'Y'
An explicit cast failed because the object’s runtime type isn’t the target type.
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.
ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection
Code accessed a List/collection position that doesn’t exist (IndexOutOfRangeException for arrays).
java.lang.IllegalArgumentException
A method rejected an argument value as invalid.
Fatal error: Uncaught Exception: message in file.php:12
An exception was thrown and nothing caught it, so PHP stopped the script.
C++: terminate called after throwing an instance of 'std::out_of_range' — what(): vector::_M_range_check
A C++ exception wasn’t caught anywhere, so std::terminate aborted the program. what() tells you the reason.
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.
API Error: Invalid state transition — operation not allowed in the resource’s current state
The request is valid, but the object is in a state where this action isn’t allowed — cancelling something already completed, refu…
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The request conflicts with the current state of the resource — e.g. a duplicate or an edit based on an outdated version.
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.
TypeError: Cannot assign to read only property 'x' of object
Code tried to modify a frozen object, a getter-only property, or immutable state.
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.
Two steps away (35)
AttributeError: 'X' object has no attribute 'y'
You accessed an attribute or method that doesn’t exist on that object type.
java.lang.ClassCastException: class A cannot be cast to class B
An object was cast to a type it isn’t.
java.lang.ArithmeticException: / by zero
Integer division or modulo by zero.
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.
java.util.ConcurrentModificationException
A collection was modified while being iterated (even in a single thread).
InvalidOperationException: Sequence contains no elements / more than one element
LINQ `First()`, `Single()`, `Last()` or `Max()` ran on an empty sequence (or `Single()` found several items).
java.lang.UnsupportedOperationException (List.of / Arrays.asList is immutable)
Code tried to modify an immutable or fixed-size collection.
HTTP 422 Unprocessable Content
The request is well-formed, but the data fails validation (e.g. invalid email, missing required field).
java.lang.NumberFormatException: For input string: "x"
A string couldn’t be parsed as a number — it’s empty, has spaces/commas, is too large, or isn’t numeric.
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.
HTTP 500 Internal Server Error
The server hit an unexpected condition — usually an unhandled exception or misconfiguration in the application.
PHP Fatal error: Allowed memory size of X bytes exhausted
The script tried to use more memory than PHP’s `memory_limit` allows.
PHP Fatal error: Uncaught Error: Call to undefined function
PHP can’t find the function you called — usually a missing extension, missing include, or namespace issue.
Segmentation fault (core dumped)
A program accessed memory it wasn’t allowed to, and the kernel killed it with SIGSEGV (exit code 139).
Fatal error: Unexpectedly found nil while unwrapping an Optional value
Swift force-unwrapped (`!`) an optional that was nil, crashing the app.
FATAL: the database system is in recovery mode
PostgreSQL crashed (often OOM-killed) and is replaying WAL to recover.
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…
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.
API Error: Resource already exists (ALREADY_EXISTS / resource_already_exists / 409)
The create request was refused because an object with the same unique identity — name, email, external ID — already exists.
HTTP 423 Locked
The resource is locked, so the change was refused — common with WebDAV files and some APIs that lock records during processing.
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.
MySQL ERROR 1062 (23000): Duplicate entry for key
An INSERT/UPDATE would create a duplicate value in a PRIMARY or UNIQUE key.
HTTP 400 Bad Request
The server could not understand the request because its syntax, headers or body are malformed or invalid.
HTTP 412 Precondition Failed
A conditional request header (If-Match, If-Unmodified-Since) didn’t match the current state of the resource.
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.
TypeError: Cannot convert undefined or null to object
Object.keys/entries/assign was called with undefined or null.
Warning: Undefined property: Class::$prop
Code read an object property that doesn’t exist on that object.
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.
Map another error
Popular: 500403400ORA-009331064Critical errorFileNotFoundException assemblyTypeError