shell bypass 403
# Errors & warnings
In addition to rule violations, stylelint surfaces the following errors and warnings:
## CSS syntax error
The chosen [PostCSS syntax](../about/syntaxes.md) was unable to parse the source.
## Parse error
The chosen [PostCSS syntax](../about/syntaxes.md) successfully parsed, but one of the construct-specific parsers failed to parse either a media query, selector or value within that source.
The construct-specific parsers are:
- `postcss-media-query-parser`
- `postcss-selector-parser`
- `postcss-value-parser`
## Unknown rule error
There is an unknown rule in the [configuration object](configure.md).
## Deprecation warning
There is a deprecated rule in the [configuration object](configure.md).
## Invalid option warning
There is a misconfigured rule in the [configuration object](configure.md).