Octave "parse error" in CI

By Kaveh Alemi·Latchkey

Octave could not parse the file. The message points at the line and column. In CI this is frequently MATLAB-only syntax that Octave does not accept, or a missing end/endfunction that a permissive local setup tolerated.

What this error means

A run stops before executing with "parse error:" and a caret pointing at the offending token, naming the file and line.

parse error:

  syntax error

>>> x = data.^2
              ^

Common causes

MATLAB-only syntax Octave rejects

Constructs like unsupported operators, string literals, or certain block forms parse in MATLAB but not in this Octave version.

A missing end or keyword

An unmatched if/for/function block, or a missing endfunction, produces a parse error at end of file.

How to fix it

Use Octave-compatible syntax

1. Read the line and column in the parse error.
2. Replace MATLAB-only syntax with an Octave-supported form.
3. Balance every if/for/while/function with its end.

Lint before running

Parse-check each file so syntax errors fail fast with a clear location.

octave-cli --eval "source('src/report.m')"

How to prevent it

• Write to the common MATLAB/Octave syntax subset when both must run.
• Balance block keywords with explicit end forms.
• Parse-check files in CI before executing them.

Frequently asked questions

Related guides

References

• GitHub Actions documentation