Error Detection

Mermaid Studio checks your diagram code as you type and highlights problems before you try to render.

Instant Feedback

As you write, errors appear immediately:

• Red underlines mark problematic code
• Error icons appear in the gutter (left margin)
• Tooltips explain what’s wrong when you hover

You don’t need to render the diagram to discover issues.

Viewing Error Details

Hover for Explanations

Move your mouse over any underlined code to see a description of the problem:

• What’s wrong with the syntax
• What the plugin expected to find
• Suggestions for fixing the issue

Error Panel

To see all problems at once:

1. Open View menu
2. Select Tool Windows and then Problems

The Problems panel lists every error and warning in your current file. Click an entry to jump directly to that line.

Common Errors Detected

Mermaid Studio catches issues like:

• Missing diagram type: Starting content without flowchart, sequenceDiagram, etc.
• Invalid syntax: Malformed node definitions or edge syntax
• Unclosed brackets: Missing ], ), or }
• Unknown keywords: Typos in diagram keywords
• Invalid characters: Characters not allowed in certain contexts

Fix Before Rendering

Errors in the preview can be confusing to debug. With real-time validation, you can:

1. See exactly where the problem is
2. Read a clear explanation
3. Fix the issue immediately
4. Watch the error disappear as you type the correction

This tight feedback loop makes writing diagrams faster and less frustrating.

Works in Markdown Too

Error detection also works in Mermaid code blocks inside Markdown files. You get the same validation and error highlighting regardless of where you write your diagrams.