USING PYCForge

Fixing conversion errors

A diagnostic identifies the source that could not convert and explains why. Start with the first error, make a focused correction, and convert again.

Variables and strings · Functions and modules · Reading and writing files

Find and fix the source

Select the diagnostic in the workspace to open its module and highlight the affected text.
Read the message and suggested correction. Keep the error code if you need to report the issue.
Compare your code with the matching example in Help.
Convert all included files again after editing. The old C output does not update until conversion succeeds.

Variable and string errors added in 1.1

Code	Check this	Typical correction
`PYC4501`	Annotation and assigned value disagree.	Keep one type per variable. Use `1.0` for `float`; assign declarations before reading them.
`PYC4502`	A constant numeric value is unsupported or out of range.	Keep integer values within signed 64-bit limits and use finite floats.
`PYC4503`	A string contains NUL or cannot be encoded as valid UTF-8.	Use valid Unicode text without embedded NUL characters.
`PYC4504`	Constant expansion exceeded a conversion limit.	Reduce repetitions, expanded strings, or source size.
`PYC4505`	A constant string operation is invalid.	Check index bounds, slice steps, method arguments, and supported methods.
`PYC4506`	An assignment target or unpacking form is unsupported.	Use scalar names and matching flat tuple/list assignments; avoid nested or starred targets.
`PYC4507`	A module value needs unsupported runtime work or mutable state.	Use constant initializers, avoid conflicting names, and pass changing values as function parameters.
`PYC4510`	A string operation received a non-string value.	Keep both operands string-valued on every path.

Other common errors

Code or family	Typical issue	Next step
`PYC100x`	Invalid conversion request or resource setting.	Try the default settings and check the requested limits.
`PYC28xx–PYC29xx`	Unsupported function, expression, call, return, or variable use.	Read the specific message and the matching reference page.
`PYC2940`	A variable may be read before assignment.	Initialize it before use on every continuing path.
`PYC2941`	A loop variable is used where it may not exist.	Initialize a separate result before the loop.
`PYC2943`	A variable changes type.	Use a consistent type in all assignments and branches.
`PYC34xx`	Unsupported container form or use.	Check Containers and records.
`PYC35xx`	Missing module, unsupported import, or conflicting name.	Add the required source file and use a direct function import.
`PYC36xx`	Unsupported record class or field access.	Use the exact simple record example.
`PYC9xxx`	Internal conversion error.	Save a minimal example, the exact message, and the installed version for a bug report.

Set errors

Use 1–64 unique literals of one numeric or Boolean type. Assign the set to a local name and use that name for membership checks. PYC3411 reports unsupported set indexing; PYC3412 reports unsupported set iteration. Use an ordered list or tuple when your program needs indexing or iteration.

File errors during conversion

Code	Typical correction
`PYC3901`	Use one direct function-body `with open` statement per session.
`PYC3902`	Do not reassign the built-in name `open`.
`PYC3903`	Check path, literal mode, `encoding='utf-8'`, and `newline=''`.
`PYC3904`	Give the handle a fresh local name.
`PYC3905`	Use one supported read or write and the documented return form.
`PYC3906`	Do not alias the handle or use it after the `with`; return a read value as documented.
`PYC3907`	Reduce the number of file operations.
`PYC3908`	Call file-access functions from the C caller, rather than another converted Python function.

Errors when the generated C runs use numeric status values instead. See Check file errors from C.

Understand the result

Converted: C was produced for the complete submitted source.
Rejected: correct the reported source issue; no new C is available.
Cancelled: conversion was stopped; start it again when ready.
Internal failure: record the error and a reproducible example.
Stale: the displayed C belongs to an earlier source or settings version. Convert again before saving it.

If a result includes warnings, review them before using the generated C.