How to fix: Use correct named group syntax?

JavaScript uses (? ...) not Python's (?P ...).

Regex Error3 Fixes Available

SyntaxError: Invalid regular expression — Invalid group

SyntaxError: Invalid regular expression: /pattern/: Invalid group

What does this error mean?

This error means your regular expression has a group syntax error. Common causes include unmatched parentheses, invalid named group syntax, or using lookahead/lookbehind incorrectly.

Common Causes

Unmatched opening ( without a closing )
Invalid named group syntax (should be (?<name>...))
Using (?P<name>...) Python syntax instead of JavaScript's (?<name>...)
Nested quantifiers like (a+)+ without proper grouping

How to Fix It (3 Solutions)

Test your regex in our Regex Tester

Our tester shows real-time errors and highlights matches as you type.

Check parentheses are balanced

Every opening ( must have a matching closing ).

Code

// ❌ Invalid
/foo(bar/

// ✅ Valid
/foo(bar)/

Use correct named group syntax

JavaScript uses (?<name>...) not Python's (?P<name>...).

Code

// ❌ Python syntax (invalid in JS)
/(?P<year>\d{4})/

// ✅ JavaScript syntax
/(?<year>\d{4})/

Fix this error faster with our free tool

Regex Tester

Open Regex Tester

Browse all error fixes