This error can appear when running build tools like Astro, Webpack, or other bundlers:

Parse failure: Unterminated string constant

The cause

This error is often caused by special characters in your file path or folder names, particularly non-ASCII characters.

This issue has been observed primarily on Windows systems.

The fix

Rename the folder you’re running the project in (or a parent folder in the path) to use only ASCII characters.

For example, change:

• Mon Projet → MonProjet or my-project
• Código → Codigo or code
• Développement → Development or dev

Other potential causes

If renaming doesn’t help, the error might also be caused by:

1. Actual unterminated strings in your code: Check for missing closing quotes

   // Bad
   const str = "Hello world
   
   // Good
   const str = "Hello world"

2. Multi-line strings without proper syntax:

   // Bad
   const str = "Line 1
   Line 2"
   
   // Good - use template literals
   const str = `Line 1
   Line 2`

3. Encoding issues: Make sure your files are saved with UTF-8 encoding

4. Copy-pasted “smart quotes”: Word processors sometimes convert straight quotes to curly quotes

   // Bad (smart quotes)
   const str = "Hello"
   
   // Good (straight quotes)
   const str = "Hello"

Lessons in this unit:

0:	Introduction
1:	"X is not a function" errors
2:	"document is not defined" error
3:	Cannot assign to read only property
4:	▶︎ Parse failure: Unterminated string constant
5:	FormData multipart fetch issues
6:	regeneratorRuntime is not defined
7:	Unexpected identifier in modules
8:	Unterminated string literal