Error map
TypeError operand TypeError: unsupported operand type(s) for +: 'int' and 'str'
Python · 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.
java.lang.ClassCastException: class A cannot be cast to class B
An object was cast to a type it isn’t.
ValueError: invalid literal for int() with base 10: 'abc'
int() received a string that isn’t a whole number — empty, decimal, whitespace or text.
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.
AttributeError: 'X' object has no attribute 'y'
You accessed an attribute or method that doesn’t exist on that object type.
TypeError: can only concatenate str (not "int") to str
You joined a string and a non-string with +.
Swift: Cannot convert value of type 'X' to expected argument type 'Y'
The value’s type doesn’t match what the function or property expects.
Rust: error[E0308]: mismatched types — expected `X`, found `Y`
A value’s type doesn’t match what the context expects — common with &str vs String, Option/Result vs plain values, and integer ty…
TypeError: 'str' object is not callable
You used parentheses on something that isn’t a function — often a variable shadowing a built-in.
TS2322: Type 'X' is not assignable to type 'Y'
You assigned a value whose type doesn’t match the declared type of the variable, property or return value.
TS2564: Property 'x' has no initializer and is not definitely assigned in the constructor
With strictPropertyInitialization on, a class property declared without ? or a default isn’t set in the constructor.
TypeError: unhashable type: 'list'
A mutable object (list, dict, set) was used as a dict key or set member.
Two steps away (34)
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.lang.ArithmeticException: / by zero
Integer division or modulo by zero.
java.lang.StringIndexOutOfBoundsException: begin 0, end 10, length 5
substring()/charAt() used an index outside the string.
java.lang.UnsupportedOperationException (List.of / Arrays.asList is immutable)
Code tried to modify an immutable or fixed-size collection.
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.
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.time.format.DateTimeParseException: Text '31/12/2024' could not be parsed at index 2
A java.time parse call got text that doesn’t match the expected format.
java.text.ParseException: Unparseable date: "x"
SimpleDateFormat couldn’t parse the string with its pattern.
OAuth Error: redirect_uri_mismatch
The redirect URI in your OAuth request doesn’t exactly match one registered for the client in the provider’s console.
hint: You have divergent branches and need to specify how to reconcile them.
Git 2.27+ asks you to choose merge, rebase or fast-forward-only when local and remote both have new commits.
error: gpg failed to sign the data — fatal: failed to write commit object
Commit signing is enabled but GPG couldn’t sign — no TTY for the passphrase, wrong key, or agent not running.
TypeError: x is not a function
You called something as a function, but its value is not a function (it’s undefined, a string, an object…).
ImportError: cannot import name 'x' from 'y'
The module was found, but the name you’re importing from it doesn’t exist — usually a version change or a circular import.
KeyError: 'x'
You accessed a dictionary key that doesn’t exist.
RangeError: Invalid string length
A string grew beyond the engine’s maximum length — usually runaway concatenation or huge JSON.stringify output.
TS7016: Could not find a declaration file for module 'x'. 'x.js' implicitly has an 'any' type.
The JavaScript package has no TypeScript types bundled and no @types package installed.
TS2304: Cannot find name 'x'.
TypeScript doesn’t know an identifier — a missing import, missing type definitions (e.g. for Node or Jest globals), or a typo.
TS2339: Property 'x' does not exist on type 'Y'.
TypeScript’s type for the object doesn’t include that property.
TS2345: Argument of type 'string | undefined' is not assignable to parameter of type 'string'.
A value’s type doesn’t match the function parameter — commonly a possibly-undefined value passed where a definite one is required.
Fatal error: Uncaught TypeError: foo(): Argument #1 ($x) must be of type int, string given
A function received a value of the wrong type for a typed parameter.
Warning: Array to string conversion
An array was used where a string is expected — echoing it, concatenating it, or passing it to a string function.
BucketAlreadyExists: The requested bucket name is not available
S3 bucket names are global across all AWS accounts, and someone else already uses this one.
CloudFormation: Resource ... already exists (AlreadyExists / already exists in stack)
The template tries to create a resource with a fixed name that already exists — created manually, by another stack, or left over…
StorageAccountAlreadyTaken: The storage account named x is already taken
Storage account names are globally unique across Azure; another customer (or you elsewhere) already uses the name.
TS18048: 'x' is possibly 'undefined'. (TS2532: Object is possibly 'undefined'.)
TypeScript requires you to handle the case where a value may be undefined before using it.
Fatal error: Uncaught Error: Cannot use object of type stdClass as array
Code used array syntax (`$x['key']`) on an object.
Fatal error: Uncaught TypeError: Unsupported operand types: string + int
An arithmetic or array operator was used with incompatible types (PHP 8 is stricter than PHP 7).
TypeError: x is not a constructor
new was used with something that isn’t a class/constructor — usually a wrong import.
Deprecated: Implicit conversion from float 2.5 to int loses precision
PHP 8.1+ warns when a float with a fractional part is silently converted to int (array keys, % operator, int parameters).
TypeError: f() takes 1 positional argument but 2 were given
A function was called with more positional arguments than it accepts — very often a method missing `self`.
java.util.ConcurrentModificationException
A collection was modified while being iterated (even in a single thread).
RuntimeError: dictionary changed size during iteration
A dict (or set) was modified while being looped over.
InvalidOperationException: Collection was modified; enumeration operation may not execute
A list/dictionary was changed while a foreach loop was iterating it.
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