Fix the pgfplots warning when input starts with equal digits.
You may see "Missing character" warnings in your log when a table cell value starts with repeated digits, such as 55.463. This happens because of a bug in how pgfplots detects headers in data tables.
The short answer: add header=false to your table options. If that doesn't work, ensure your data is clean or use a newer version of the package.
Summarize with AI:
Why this warning appears
The warning occurs because pgfplots tries to determine if a row contains column names by testing the cell contents. It uses a macro called \pgfplotstableread@if@finite that performs an \ifx test on the input.
When your data starts with two identical digits, like 55.463, the internal logic incorrectly identifies the cell as a header. This leads to the engine trying to typeset parts of the number as if they were text in a font that lacks those characters, triggering the missing character errors.
How to fix the issue
| Fix | When to use |
|---|---|
Add header=false | When your table has no header row. |
| Update pgfplots | If you are on an older version of TeX Live 2026. |
| Pre-process data | If you must keep headers and the bug persists. |
There are several ways to stop these warnings depending on your document structure.
Using header=false
| Code |
|---|
| \addplot table[header=false, x index=0, y index=1] {data.csv}; |
If you are loading data from a file or inline block that does not contain column names, explicitly telling pgfplots to skip header detection is the safest fix.
Questions
Is my data corrupted because of this warning?
No. The warning is a side effect of the internal header detection logic. Your plot should still render correctly, though the log file will be cluttered with warnings.
Does this only happen with the number 55?
No. Any value starting with two identical digits, such as 11.2, 22.5, or 550, can trigger this behavior depending on how the table is parsed.
Will updating my TeX distribution help?
Yes. This is a known issue in the pgfplots package. Texeno uses TeX Live 2026, which includes the most recent patches and fixes for these types of parsing bugs.
Can I ignore these warnings?
You can, but it is better to fix them. If you have many such values, the warnings can make it difficult to spot actual errors in your LaTeX code.
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