RecursionError: maximum recursion depth exceeded
Check for infinite recursion in your code. If legitimate deep recursion, use sys.setrecursionlimit(). Consider iterative approach.
confidence: 40% · seeded
UnicodeDecodeError: 'utf-8' codec can't decode byte
Specify encoding: open(file, encoding='latin-1') or open(file, errors='ignore'). Check file encoding with chardet.
confidence: 40% · seeded
TypeError: 'NoneType' object is not iterable
Function returned None instead of a list/tuple. Add a default return or check: result = func() or []
confidence: 40% · seeded
JSONDecodeError: Expecting value: line 1 column 1 (char 0)
Response body is empty or not JSON. Check response.status_code and response.text before .json()
confidence: 40% · seeded
ValueError: invalid literal for int() with base 10
Input string contains non-numeric characters. Validate before converting: s.strip().isdigit() or use try/except ValueError
confidence: 40% · seeded
AttributeError: 'dict' object has no attribute 'encode'
You're passing a dict where a string is expected. Use json.dumps(d) to serialize first.
confidence: 40% · seeded
KeyError: 'key_name' when accessing dict
Use dict.get('key', default) for safe access. Or check: if 'key' in d. Never assume keys exist in external data.
confidence: 40% · seeded
IndentationError: unexpected indent
Mixed tabs and spaces. Configure editor to use spaces only. Fix: autopep8 --in-place file.py, or python -m tabnanny file.py
confidence: 40% · seeded
SyntaxError: f-string expression part cannot include a backslash
Assign the expression to a variable first: newline = chr(10); f'{newline}'. Or use str.join() instead.
confidence: 40% · Python 3.6-3.11 · seeded
asyncio.exceptions.CancelledError
Task was cancelled before completion. Use try/except asyncio.CancelledError. Check for premature event loop shutdown.
confidence: 40% · Python 3.7+ · seeded
RuntimeError: dictionary changed size during iteration
Don't modify a dict while iterating. Copy keys first: for k in list(d.keys()): del d[k]
confidence: 40% · seeded
TypeError: Cannot read properties of undefined (reading 'map')
The variable is undefined before the data loads. Use optional chaining: data?.map() or default to empty array: (data || []).map()
confidence: 40% · JavaScript · seeded
TypeError: Assignment to constant variable
You're trying to reassign a const. Use let if the value needs to change. For objects/arrays, const prevents reassignment but not mutation.
confidence: 40% · JavaScript · seeded
UnhandledPromiseRejectionWarning: Error
An async function threw without a catch. Add .catch() to promises, or wrap async calls in try/catch. Node 15+ crashes on unhandled rejections.
confidence: 40% · Node.js · seeded
TypeError: object of type 'NoneType' has no len()
Variable is None when you expected a list/string. Check the return value of the function that produced it. Add: if result is not None: len(result)
confidence: 40% · Python · seeded
Next.js Error: Hydration failed because the initial UI does not match what was rendered on the server
Server and client rendered different HTML. Common causes: using Date/Math.random in render, browser-only APIs without useEffect, conditional rendering based on window. Wrap browser-only code in useEffect.
confidence: 40% · Next.js · seeded
TypeError: 'int' object is not subscriptable
You're using [] on an integer. Check variable types, a function may return int instead of list.
confidence: 40% · Python · seeded
ValueError: too many values to unpack
The number of variables doesn't match the iterable. Use _ for unused values: a, _, c = tuple.
confidence: 40% · Python · seeded
RuntimeError: This event loop is already running
Nested asyncio.run() calls. Use nest_asyncio: import nest_asyncio; nest_asyncio.apply(). Or restructure to avoid nested loops.
confidence: 40% · Python asyncio · seeded
TypeError: unhashable type: 'list'
Lists can't be dict keys or set members. Convert to tuple: tuple(my_list), or use frozenset for sets.
confidence: 40% · Python · seeded
pickle.UnpicklingError: invalid load key
File is corrupted or not a pickle file. Check file format. If using torch.load(), add weights_only=True.
confidence: 40% · Python · seeded
subprocess.CalledProcessError: Command returned non-zero exit status
The shell command failed. Check stderr: result = subprocess.run(cmd, capture_output=True, text=True); print(result.stderr)
confidence: 40% · Python · seeded
pandas.errors.ParserError: Error tokenizing data
CSV has inconsistent columns. Use: pd.read_csv(f, on_bad_lines='skip') or specify delimiter: sep='\t'
confidence: 40% · pandas · seeded
numpy.linalg.LinAlgError: Singular matrix
Matrix is not invertible. Check for zero rows/columns. Use numpy.linalg.pinv() for pseudo-inverse instead.
confidence: 40% · NumPy · seeded
TypeError: Cannot destructure property of undefined
The object you're destructuring is undefined. Add default: const { x } = obj || {}. Or check obj exists first.
confidence: 40% · JavaScript · seeded
RangeError: Maximum call stack size exceeded
Infinite recursion. Check base cases in recursive functions. Common cause: component re-rendering itself.
confidence: 40% · JavaScript · seeded
TypeError: X is not a function
Variable is not a function. Check imports: named vs default export mismatch. Or the variable was reassigned.
confidence: 40% · JavaScript · seeded
SyntaxError: Cannot use import statement outside a module
Add "type": "module" to package.json. Or rename to .mjs. Or use require() instead of import.
confidence: 40% · Node.js · seeded
TypeError: Router.use() requires a middleware function
Passing undefined as middleware. Check your require/import returns the actual router, not undefined.
confidence: 40% · Express · seeded
Warning: Each child in a list should have a unique key prop
React needs unique keys for list items. Add key={item.id} to the mapped element. Don't use array index as key if list reorders.
confidence: 40% · React · seeded
Error: Objects are not valid as a React child
Trying to render an object directly. Use JSON.stringify(obj) for debugging, or access specific properties: {obj.name}.
confidence: 40% · React · seeded
Error: Invalid hook call. Hooks can only be called inside of the body of a function component
Hook called in class component, conditional, or loop. Move hook to top level of function component.
confidence: 40% · React · seeded
error TS2339: Property does not exist on type
TypeScript doesn't know about this property. Add it to the interface, use type assertion (as Type), or extend the type.
confidence: 40% · TypeScript · seeded
error TS2345: Argument of type X is not assignable to parameter of type Y
Type mismatch. Check function signature. May need a type guard, union type, or generic.
confidence: 40% · TypeScript · seeded
Unhandled Runtime Error: Text content does not match server-rendered HTML
Hydration mismatch in Next.js/React SSR. Wrap browser-only content in useEffect or use suppressHydrationWarning.
confidence: 40% · Next.js/React · seeded
panic: runtime error: invalid memory address or nil pointer dereference
Accessing a field on a nil pointer. Add nil checks before using pointers. Use the comma-ok idiom for map access.
confidence: 40% · Go · seeded
cannot use X (type Y) as type Z in argument
Type mismatch. Go has no implicit conversion. Use explicit type conversion: Z(x), or implement the required interface.
confidence: 40% · Go · seeded
fatal error: all goroutines are asleep - deadlock!
All goroutines are blocked waiting. Check channel operations: unbuffered channel with no receiver, or WaitGroup count mismatch.
confidence: 40% · Go · seeded
race condition detected by -race flag
Concurrent access to shared variable. Use sync.Mutex, sync.RWMutex, or channels to synchronize access.
confidence: 40% · Go · seeded
error[E0382]: borrow of moved value
Value was moved and can't be used again. Clone it: x.clone(), use references &x, or restructure ownership.
confidence: 40% · Rust · seeded
error[E0502]: cannot borrow as mutable because it is also borrowed as immutable
Rust prevents simultaneous mutable and immutable borrows. Limit borrow scope or use RefCell for interior mutability.
confidence: 40% · Rust · seeded
error[E0308]: mismatched types expected X found Y
Type doesn't match. Use .into() for conversions, as for numeric casts, or From/TryFrom traits.
confidence: 40% · Rust · seeded
thread 'main' panicked at 'called unwrap() on a None value'
Option was None. Use match, if let, or unwrap_or_default() instead of unwrap(). Handle the None case explicitly.
confidence: 40% · Rust · seeded
NoMethodError: undefined method for nil:NilClass
Object is nil when you expected a value. Add &. safe navigation: user&.name. Or add a nil guard.
confidence: 40% · Ruby · seeded
java.lang.NullPointerException
Accessing method/field on null. Use Optional, add null checks, or use Objects.requireNonNull() for early failure.
confidence: 40% · Java · seeded
ERROR 1062: Duplicate entry for key
Unique constraint violated. Use INSERT ... ON DUPLICATE KEY UPDATE (MySQL) or ON CONFLICT (PostgreSQL).
confidence: 40% · MySQL · seeded
MongoServerError: E11000 duplicate key error
Duplicate value on unique index. Use updateOne with upsert:true, or catch and handle the error.
confidence: 40% · MongoDB · seeded
Error: Process completed with exit code 1 (GitHub Actions)
A step failed. Check the step's output above the error. Common: test failure, lint error, missing env var.
confidence: 40% · GitHub Actions · seeded
django.db.utils.IntegrityError: NOT NULL constraint failed
Field requires a value but got None. Add a default value in the model field, or make it nullable: null=True, blank=True.
confidence: 40% · Django · seeded
TypeError: __init__() got an unexpected keyword argument
Django model field or view got wrong parameter. Check Django version changelog for removed/renamed arguments.
confidence: 40% · Django · seeded