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Python Console Window Closes Immediately: How to Fix

The console window belongs to the process: the script ends, the window disappears along with the traceback. Why that happens, how to run the file from cmd or PowerShell, what the py launcher is for, and how to redirect output and errors to a file. Plus the case where nothing failed at all.

29 Iúil 2026PythonerrorstracebackWindows

Python TabError: Mixed Tabs and Spaces in Indentation

TabError shows up when one block of code is indented with both tabs and spaces. On screen the two look identical, so you cannot find the bug by reading the file. Here is how to render whitespace, convert the file in one command, and configure the editor so it never happens again.

29 Iúil 2026PythonerrorsindentationTabError

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ValueError: could not convert string to float in Python

ValueError: could not convert string to float almost always means one thing: float() got a string with a decimal comma such as 77,59. This walks through the comma, the empty string, the invisible Excel BOM and the non-breaking space, and builds a price parser that survives dirty data.

29 Iúil 2026PythonerrorsValueErrorstrings

How to Remove a File Extension From a String in Python

rstrip('.txt') does not remove an extension: it chews a character set, so report.txt silently becomes repor. Here is the mechanism plus four correct approaches — removesuffix, os.path.splitext, Path.stem and slicing. Edge cases too: archive.tar.gz, .gitignore and extensionless files.

29 Iúil 2026Pythonstringspathlibfiles

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list indices must be integers or slices, not str — Fix

TypeError: list indices must be integers or slices, not str means you indexed a list with a string key. The usual cause is JSON: parsing returned a list of dictionaries, so data['name'] has to become data[0]['name']. Inside: the one-line diagnosis, the mirror error string indices must be integers, and how it differs from KeyError and IndexError.

29 Iúil 2026PythonerrorsTypeErrorJSON

Deleting From a List While Looping Skips Items in Python

A for loop walks a list by an internal index while remove() and del shift the tail left, so one element slips past the check after every deletion. Nothing is raised and the list comes back half-filtered. Here is the mechanism step by step plus three fixes that work.

29 Iúil 2026Pythonlistsloopsiteration

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Python for Loop Variable Does Not Change the List: Fixes

A Python for loop variable is a separate name, not a slot in the list, so assigning to it changes nothing and raises no error. The article separates rebinding a name from mutating an object, and shows why a nested list can be changed in the same loop while a number cannot. Three working fixes are included: index writes, comprehensions and slice assignment.

29 Iúil 2026Pythonloopslistsmutability

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Python TypeError: unhashable type 'list' — How to Fix It

TypeError: unhashable type: 'list' shows up when a list lands in a dict key, a set, or an in test against a set. Here is what hashable really means, why a tuple works where a list fails, and how to fix deduplicating a list of lists, grouping by a composite key, and using a dict as a key.

29 Iúil 2026Pythonerrorsdictset

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Python UnicodeDecodeError Reading a File: cp1251 vs UTF-8

Mojibake instead of Cyrillic and a crash with UnicodeDecodeError are the same bug: Python assumed the wrong encoding. Why open() has no fixed default, how to read the whole error message, and how utf-8-sig differs from utf-8. Every snippet runs as written.

29 Iúil 2026Pythonencodingfileserrors

Python JSON: Cyrillic Saved as Unicode Escapes — Fix

Your JSON file stores the word for coffee as \u043a\u043e\u0444\u0435, which is default json.dump behaviour rather than damage. Here is what ensure_ascii controls, what encoding controls, and why you need both at once.

29 Iúil 2026Pythonjsonencodingunicode