Error map
UnsupportedOperationException java.lang.UnsupportedOperationException (List.of / Arrays.asList is immutable)
Java · layer 4, Application & API
Centre: this error. First ring: errors it is linked with (9). 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 (9)
java.lang.ClassCastException: class A cannot be cast to class B
An object was cast to a type it isn’t.
java.util.ConcurrentModificationException
A collection was modified while being iterated (even in a single thread).
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.
RuntimeError: dictionary changed size during iteration
A dict (or set) was modified while being looped over.
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.ArithmeticException: / by zero
Integer division or modulo by zero.
InvalidOperationException: Collection was modified; enumeration operation may not execute
A list/dictionary was changed while a foreach loop was iterating it.
TypeError: unhashable type: 'list'
A mutable object (list, dict, set) was used as a dict key or set member.
Two steps away (27)
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.
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.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.
Warning: Undefined array key / Undefined index
Your code reads an array key that doesn’t exist — common with `$_GET`, `$_POST` and decoded JSON.
[ERROR] Fatal error compiling: error: release version 17 not supported
The JDK running Maven is older than the Java version the project compiles for.
TypeError: Reduce of empty array with no initial value
Array.reduce() ran on an empty array without an initial value.
npm ERR! code EACCES — permission denied
npm can’t write to a directory — usually global installs into a root-owned folder.
Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?
The docker CLI can’t talk to the Docker engine — it isn’t running, or your user can’t access the socket.
Linux: Permission denied
Your user (or the service user) lacks read/write/execute permission on a file, directory or one of its parents.
AttributeError: 'X' object has no attribute 'y'
You accessed an attribute or method that doesn’t exist on that object type.
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.
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.IllegalArgumentException
A method rejected an argument value as invalid.
java.lang.IllegalStateException
A method was called when the object wasn’t in the right state for it.
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.util.InputMismatchException (Scanner)
Scanner.nextInt()/nextDouble() read a token that isn’t that type.
MySQL ERROR 1690 (22003): BIGINT UNSIGNED value is out of range
Arithmetic on UNSIGNED columns produced a negative result.
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.
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.
TypeError: unsupported operand type(s) for +: 'int' and 'str'
An operator was used between two incompatible types, such as adding a number to a string.
TypeError: can only concatenate str (not "int") to str
You joined a string and a non-string with +.
TypeError: 'str' object is not callable
You used parentheses on something that isn’t a function — often a variable shadowing a built-in.
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