How to Fix "MemoryError" When Processing Large Files in pandas/Python
Loading a large CSV or dataset into pandas crashes the process instead of completing, because the entire file is being loaded into RAM at once and there simply...
Category
Python
Tracking down Python errors, packaging and environment problems.
How to Resolve "ImportError: Cannot Import Name X From Partially Initialized Module"
An import that should work fine fails with a message specifically mentioning a "partially initialized module," which is Python's precise way of describing a...
Python FastAPI "422 Unprocessable Entity" on Valid JSON Payload
FastAPI's 422 response always includes a detailed body explaining exactly which field failed validation and why — the fix almost always starts with actually...
Python ModuleNotFoundError When Running Script From a Parent Folder
A script that imports fine when run from one directory but fails with ModuleNotFoundError when run from a different directory (particularly a parent folder)...
Python Multiprocessing Pool Hang or Freeze on Exception
A multiprocessing.Pool that hangs indefinitely rather than raising an exception when a worker function fails is a well-known and common pattern, particularly...
Python "PermissionError: [Errno 13] Permission Denied" When Writing File
A PermissionError when writing a file means the operating system, not Python itself, is refusing the write — the fix requires identifying whether the issue is...
Python requests Library Connection Pool Full Warning Under Heavy Load
The "Connection pool is full, discarding connection" warning from urllib3 (used internally by the requests library) means your application is making more...
Python FastAPI Background Task Not Running After Returning Response
A FastAPI background task that seems to never run, despite being correctly added to the request, usually comes down to either an incorrect function signature...
Python json.dumps() TypeError: Object of Type datetime Is Not JSON Serializable
Python's built-in json module has no built-in support for serializing datetime objects (or several other common Python types) — JSON itself has no native...