# Negative lookbehind not working in watched words regex

**URL:** https://meta.discourse.org/t/negative-lookbehind-not-working-in-watched-words-regex/271981
**Category:** Support
**Tags:** watched-words
**Created:** [July 18, 2023, 12:56pm UTC](https://meta.discourse.org/t/negative-lookbehind-not-working-in-watched-words-regex/271981 "2023-07-18T12:56:06Z")
**Posts on this page:** 1
**Showing post:** 8

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### Author: ![tkrunning](https://sea3.discourse-cdn.com/meta/user_avatar/meta.discourse.org/tkrunning/32/119481_2.png) [@tkrunning](https://meta.discourse.org/u/tkrunning)
#### Post date: [August 3, 2023, 10:24am UTC](https://meta.discourse.org/t/negative-lookbehind-not-working-in-watched-words-regex/271981/8 "2023-08-03T10:24:38Z")

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Turns out it’s only supported from Safari 16.4, and I had 16.3.

Still causing other issues for me, though (like can’t save my user preferences):

> [@What could be causing 500 errors when saving user preferences?](https://meta.discourse.org/t/what-could-be-causing-500-errors-when-saving-user-preferences/273790/3):
>
> So I guess it might actually have been this error: I figured that one was just showing up due to this issue: However, it turns out it’s all related. Here are the full logs: Info: RegexpError (invalid pattern in look-behind: /((?\<!estonia.\*\s)\be-residence\b(?!.\*estonia))/i) app/services/word\_watcher.rb:264:in `initialize' app/services/word_watcher.rb:264:in `new' app/services/word\_watcher.rb:264:in `block in replace' app/services/word\_watcher.rb:262…

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