Error map
Index was out of range ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection
.NET · 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)
Thread 1: signal SIGABRT (app crashes with "libc++abi: terminating")
The app deliberately aborted — an uncaught exception, failed assertion or fatalError. The console above the crash has the real me…
java.lang.IllegalArgumentException
A method rejected an argument value as invalid.
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.
java.lang.UnsupportedOperationException (List.of / Arrays.asList is immutable)
Code tried to modify an immutable or fixed-size collection.
Fatal error: Uncaught Exception: message in file.php:12
An exception was thrown and nothing caught it, so PHP stopped the script.
java.lang.IllegalStateException
A method was called when the object wasn’t in the right state for it.
java.util.ConcurrentModificationException
A collection was modified while being iterated (even in a single thread).
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.
RuntimeError: dictionary changed size during iteration
A dict (or set) was modified while being looped over.
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.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.
java.lang.ArithmeticException: / by zero
Integer division or modulo by zero.
Two steps away (33)
Fatal error: Unexpectedly found nil while unwrapping an Optional value
Swift force-unwrapped (`!`) an optional that was nil, crashing the app.
Thread 1: EXC_BAD_ACCESS (code=1, address=0x0)
The app accessed memory it shouldn’t — a dangling pointer, released object, unsafe pointer misuse, a data race, or infinite recur…
NSUnknownKeyException: this class is not key value coding-compliant for the key x
A storyboard/XIB has a connection to an outlet or action that no longer exists in the class (renamed or deleted), or the view’s c…
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.
MethodArgumentNotValidException: Validation failed for argument [0]
Bean Validation (@Valid with @NotNull, @Email, @Size…) rejected the request body.
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.
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.
java.lang.ArrayIndexOutOfBoundsException: Index 5 out of bounds for length 5
Code accessed an array index outside 0 … length-1.
java.nio.file.AccessDeniedException: /path
The OS denied a file operation to the Java process.
TypeError: unhashable type: 'list'
A mutable object (list, dict, set) was used as a dict key or set member.
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.
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.
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.
java.lang.NullPointerException
Code called a method or accessed a field on a reference that is `null`.
java.lang.OutOfMemoryError: Java heap space
The JVM ran out of heap memory and garbage collection couldn’t free enough.
java.lang.InterruptedException (sleep interrupted)
A blocked thread (sleep, wait, join, queue take) was interrupted by another thread.
Segmentation fault (core dumped)
A program accessed memory it wasn’t allowed to, and the kernel killed it with SIGSEGV (exit code 139).
FATAL: the database system is in recovery mode
PostgreSQL crashed (often OOM-killed) and is replaying WAL to recover.
Illegal instruction (core dumped) (SIGILL)
The program used a CPU instruction your processor doesn’t support — typically AVX/AVX2 in prebuilt binaries (TensorFlow, MongoDB…
TypeError: x is not iterable
for…of, spread or destructuring was used on something that isn’t an array/iterable.
ConnectionRefusedError: [Errno 111] Connection refused
Nothing is listening on the host/port Python tried to connect to.
RuntimeError: Event loop is closed
Async code tried to use an event loop that has already been shut down.
System.NullReferenceException: Object reference not set to an instance of an object
Code dereferenced a variable that is `null` — the .NET equivalent of Java’s NullPointerException.
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.
EF Core: The LINQ expression 'x' could not be translated. Either rewrite the query in a form that can be translated, or switch to client evaluation explicitly
The query uses C# code EF Core can’t convert to SQL — custom methods, unsupported string/date functions, or complex projections.
java.lang.StringIndexOutOfBoundsException: begin 0, end 10, length 5
substring()/charAt() used an index outside the string.
java.io.IOException: Stream closed
Code read or wrote a stream after it was closed — often by a try-with-resources block or a wrapper closing the underlying stream.
[ERROR] Fatal error compiling: error: release version 17 not supported
The JDK running Maven is older than the Java version the project compiles for.
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