docusaurus "MDX compilation failed" unexpected character error

Fix Docusaurus "MDX compilation failed" unexpected character errors

TL;DR

MDX treats curly braces as JavaScript expressions, so a literal { or } in prose (or one unclosed code fence) breaks parsing at the reported line. Wrap literal braces in code spans or escape them as {'{'} {'}'} style expressions, close the fence, then rebuild. The file compiles because the parser no longer sees stray expression syntax.

The error

[MDXCompilationError] Docusaurus MDX loader failed to parse markdown content in docs/guide.md:
Unexpected character `{` (1:42)

Steps

1. Read the error: it names the file and the exact line and column of the offending character.

Expected: you can point at the specific character in the source file.

1. Fix the character: wrap literal braces in backtick code spans, or escape them as MDX expressions like {'{'} and {'}'}. Bare braces only survive inside code spans, fenced code blocks, or real JSX expressions.

Expected: no bare curly braces remain in prose.

1. Check for an unclosed code fence above the error line: one missing closing fence makes the rest of the file parse as code and the error surfaces far from the real problem. Count the fences.

Expected: every opening fence has a matching closing fence.

1. Rebuild: npm run build.

Expected: MDX compiles the file and the build continues past it.

Use this when

• MDXCompilationError naming a file, line, and column
• docs showing JSON snippets or template syntax with literal braces
• a page that broke right after a code block was edited

Not for this skill when

• 'broken markdown link' (the file parses fine; a link target is wrong)
• 'plugin not found' (dependency/config problem)
• a blank page with no build error (rendering problem, not a parse problem)

Variant phrasings

• docusaurus MDX compilation failed
• docusaurus unexpected character MDX
• docusaurus could not parse markdown content
• mdx loader failed docusaurus curly brace

Why it happens

Docusaurus pages are MDX, which is Markdown plus JSX: the compiler scans prose for { } expression boundaries and JSX-style tags. A literal brace in normal text - common in JSON examples, config snippets, or template placeholders - opens an expression the parser cannot close, so it reports an unexpected character. An unclosed code fence is the sneakier variant: everything after it is treated as code until the next fence, and the parse error lands far from the missing fence.

Edge cases

• import and export statements are only allowed at the top of an MDX file; one buried mid-page throws a different MDX error.
• JSX-style tags in prose must be valid or wrapped in code spans; an unclosed tag swallows the following paragraphs.
• If a page needs lots of literal braces, prefer a fenced code block over inline escapes - it is easier to read and cannot break parsing.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_7ZziPwBN97Q6MgBf7z7bpA