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Python

TypeError: unsupported operand type(s) for +: 'int' and 'str'

Python 3

TypeError: unsupported operand type(s) for +: 'int' and 'str' (or a similar type combination).

What it means (root cause)

An operation combines incompatible types — most often concatenating a string with a non-string (f-strings or str() fix it), or calling a method on a None that resulted from a failed parse.

The symptom developers actually see: TypeError: unsupported operand type(s) for +: 'int' and 'str' (or a similar type combination).

How to avoid it: Parse and validate types at the boundary; use f-strings for concatenation so the conversion is explicit.

Step-by-step fix

Concrete, ordered steps from the dataset. Apply them in order; each line is a verified action, not generic advice.

  1. 1Make types explicit: str(x) + y, or use an f-string f'{x}{y}' for concatenation.
  2. 2Check the value is not None before calling a method on it (a failed API parse often returns None).
  3. 3For numeric math, cast inputs with int()/float() after validating they parse.

Where this error appears

Languages, frameworks, and runtimes where this error is observed (from the 2026 DevFixPro error dataset, retrieved 2026-08-29):

Python 3

Python 3. Unlike JS, Python does not implicitly coerce types in arithmetic or string concatenation.

How to prevent it & common questions

Practical prevention plus the questions developers ask most about this error.

What does "TypeError: unsupported operand type(s) for +: 'int' and 'str'" mean?

An operation combines incompatible types — most often concatenating a string with a non-string (f-strings or str() fix it), or calling a method on a None that resulted from a failed parse.

Which environments are affected by TypeError: unsupported operand type(s) for +: 'int' and 'str'?

Python 3

How do I fix TypeError: unsupported operand type(s) for +: 'int' and 'str'?

Make types explicit: str(x) + y, or use an f-string f'{x}{y}' for concatenation. Check the value is not None before calling a method on it (a failed API parse often returns None). For numeric math, cast inputs with int()/float() after validating they parse.

How do I prevent TypeError: unsupported operand type(s) for +: 'int' and 'str'?

Parse and validate types at the boundary; use f-strings for concatenation so the conversion is explicit.

Why can't I add a string and an int?

Python does not auto-coerce. Convert explicitly: str(n) + s, or f'{n}{s}'. The TypeError prevents silent, wrong results.

Where does the None come from?

Often a failed int()/float() or a missing dict key returned None; guard the parse before you operate on the value.

Related DevFixPro tools

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● Data updated 2026-08-29

Sources & attribution

  • Error records aggregated from Google Search Console query gaps (2026-05-21~2026-08-18) for devfixpro.com, plus official framework docs (MDN, Node.js docs, Python docs, Go.dev, Rust book, Oracle Java docs, Docker docs, npm docs). Source dataset retrieved 2026-08-29. License: CC BY 4.0 — attribute DevFixPro (devfixpro.com).
  • Official reference: https://docs.python.org/3/library/exceptions.html#TypeError
  • All cause, environment, fix and prevention text on this page is taken verbatim from the DevFixPro 2026 error dataset. DevFixPro does not invent root causes or fixes.
How this TypeError: unsupported operand type(s) for +: 'int' and 'str' page is built

Each error page is generated from a single record in the DevFixPro 2026 error dataset. The meaning, root cause, environments, fix steps, prevention, and official references are copied verbatim from that dataset and its official-doc sources; related-error links are computed from the error's category and explicit peer list. No root cause or fix is invented. The retrieval date for this dataset is 2026-08-29.

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