Error map
409 HTTP 409 Conflict
HTTP · layer 2, Network
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 400 Bad Request
The server could not understand the request because its syntax, headers or body are malformed or invalid.
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.
MySQL ERROR 1062 (23000): Duplicate entry for key
An INSERT/UPDATE would create a duplicate value in a PRIMARY or UNIQUE key.
java.lang.IllegalStateException
A method was called when the object wasn’t in the right state for it.
java.util.concurrent.TimeoutException
A Future.get(timeout) or async operation didn’t complete in the allowed time.
Operation cannot be fulfilled on deployments.apps "x": the object has been modified; please apply your changes to the latest version and try again
Optimistic-concurrency conflict: the object changed (new resourceVersion) between when you read it and when you tried to update i…
Go: fatal error: all goroutines are asleep - deadlock!
Every goroutine is blocked waiting (on a channel, mutex or WaitGroup), so the program can never continue.
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.
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…
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…
EF Core: A second operation was started on this context instance before a previous operation completed
The same DbContext was used concurrently — async calls not awaited, parallel tasks sharing a context, or a context registered as…
Two steps away (36)
HTTP 401 Unauthorized
The request has no valid authentication credentials — you need to log in or send a valid token.
HTTP 405 Method Not Allowed
The URL exists, but it doesn’t accept the HTTP method you used (e.g. POST to a GET-only route).
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.
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…
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.
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.
TypeError: Cannot assign to read only property 'x' of object
Code tried to modify a frozen object, a getter-only property, or immutable state.
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.
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.
Subquery returns more than 1 row (MySQL 1242) / more than one row returned by a subquery used as an expression
A subquery used where a single value is expected (`= (SELECT …)`) returned several rows.
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.
HTTP 408 Request Timeout
The server closed the connection because the client took too long to send the complete request.
HTTP 504 Gateway Timeout
A proxy or gateway waited too long for the upstream server to respond and gave up.
HTTP 499 Client Closed Request (Nginx)
Nginx-specific code logged when the client disconnected before the server finished responding.
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.
java.lang.InterruptedException (sleep interrupted)
A blocked thread (sleep, wait, join, queue take) was interrupted by another thread.
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.
ERROR: could not serialize access due to concurrent update
A REPEATABLE READ/SERIALIZABLE transaction conflicted with a concurrent one and must be retried.
API Error: Idempotency key reused with different parameters (idempotency_key_in_use)
An Idempotency-Key header was sent again with a different request body, or while the first request with that key was still runnin…
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: 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: 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.
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.
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.
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.
InvalidOperationException: Unable to resolve service for type 'X' while attempting to activate 'Y'
ASP.NET Core’s dependency injection container can’t build Y because one of its constructor dependencies (X) was never registered.
API Error: Too many concurrent requests (concurrency limit reached)
You have more requests in flight at once than the API allows for your key — even if your requests-per-minute rate is fine.
ConditionalCheckFailedException: The conditional request failed
A write’s ConditionExpression evaluated to false, so DynamoDB didn’t perform it — often exactly as designed.
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