KumaScript errors appearing on a page can be very off-putting to readers, in their big scary red boxes, but fortunately anyone with an MDN account can edit a document to fix such an error. When a page has an error it gets added to the list of documents with errors.  Site editors go through this list regularly to find and fix errors. This article details the four types of KumaScript error, and some steps you can take to fix them.


DocumentParsingError errors appear when KumaScript has trouble understanding something in the document itself. The most common cause is a syntax error in a macro.

Check for:

Use of curly braces without intending to call a macro.
If you need to write  { in a document without calling a macro you can escape it with a \ like this: \{
Use of a special character in a macro parameter.
If you need to use a " or a \  inside of a macro parameter they can be escaped with a \ like this: \\ or \"
Missing commas between macro parameters.
Macro parameters need to be delimited by a comma (,) but not at the end of the list of parameters; for example {{anch("top", "Back to top")}}.
HTML tags appearing inside a macro call
If you apply styling to a macro, it will often break because, for example, a </code> tag may have appeared inside the macro code in the source code. Check the source view to see what's there, and remove any unnecessary styling.


TemplateLoadingError errors appear when KumaScript has trouble finding which macro to include on a page.

Check for:

Misspelling of macro names or renamed macros.
You can try visiting the template page for the macro to see if it's named correctly. The URL for the template page can be constructed by adding the template name to the end of the URL https://developer.mozilla.org/en-US/docs/Template: — for example the template page for {{anch("top", "Back to top")}}  is https://developer.mozilla.org/en-US/docs/Template:anch.

There is a partial list of macros for the MDN, which may include the existing macro you are looking at, or its correct/new spelling.

Tip: You can make it quick and easy to jump to a specific macro by adding a search keyword to Firefox. See "Using search keywords to open template pages" in KumaScript for a step-by-step guide to creating the search keyword for this.


TemplateExecutionError errors appear when KumaScript encounters an error in the macro. These errors can only be fixed by admin users and need to be reported as bugs.

Before reporting an error check to see that it hasn't already been fixed. You can do this by forcing KumaScript to give you a fresh copy of the page by holding down Shift while you refresh the page (Shift + Ctrl + R on Windows/Linux, Shift + Cmd + R on Mac).

If the error persists, report a bug, including the URL of the page and the text of the error.

Error & Unknown

This is the category errors end up in if they are not one of the other kinds of error.

Check for fixes and report persistent bugs like described under TemplateExecutionError.

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 Last updated by: Sheppy,